Chief among them is the notorious bunch of grumps known as the Group Really Into Negating Christmas Happiness, or GRINCH for short.
GRINCH has been around for many years, doing whatever it can to make Christmas an unhappy day.
Its main aim is to stop Santa delivering toys to the millions of loving children around the world who get up on Christmas morning, hoping to see their stockings brimming with goodies.
An empty stocking means tears, leaving many children feeling they hadn't been good enough that year to deserve a visit from Santa.
GRINCH knows only too well that if it can stop Santa's deliveries, Christmas will be a miserable day for countless thousands of families.
GRINCH started off with small stuff. For example, one year its agents loosened the bolts on the skids of Santa's sleigh. Santa detected the problem on his pre-flight checks and it was quickly fixed.
Another year they tried to spike the reindeer's food with a laxative to make them too unwell for their round-the-world journey. Security cameras picked up the intruders and they were quickly banished from Santa's Arctic wonderland.
As the years passed, GRINCH became more radical and began hatching ever-more-evil plans to ruin Christmas.
Santa was well aware of the threat, and a secret division within Christmas Inc, the multinational corporation he established to help him make and deliver presents, is dedicated to monitoring nasty groups such as GRINCH.
Elves around the world are constantly listening to chatter over the airwaves, trying to get a heads-up on what groups such as GRINCH are up to next.
If a threat is identified, Christmas Inc notifies the government of the country involved, which then hunts down and arrests those responsible. After all, what country would want to see Christmas ruined because it failed to act on Santa's intelligence?
GRINCH is headed by a malcontent with the unlikely name of Ebenezer Killjoy. Ruining Christmas is a total obsession with him.
In recent years, he has not been afraid to resort to violence to achieve his ends. Each year, Santa's elves have been on to him, and the threats have been averted.
However, in 2009, GRINCH hatched a plan so evil that even the United States Government couldn't guarantee it could eliminate the threat.
Santa was worried.
The plan, if successful, would see millions of families on the US western seaboard miss out on Christmas presents ...
A worried elf knocked and entered Santa's office. It was just 12 days before Christmas, and, as you can imagine, Santa had much to do.
"Good morning, Terry," said Santa, who knew the names of all the thousands of elves who worked for Christmas Inc.
Terry headed up special ops for Christmas and it was clear something was wrong.
"It's GRINCH," Terry said. "Their latest plan is the most terrible yet!"
Terry outlined how his staff had intercepted secret radio chatter indicating GRINCH had a plan to destroy Christmas for each and every family living in the western United States.
It is a little known fact that Santa doesn't leave the North Pole with all the toys needed to complete his deliveries. There are simply too many.
Instead, he ships tens of thousands of toys to the US eastern seaboard. From there, they are loaded on to five freight trains and discreetly carried across the US in a rail convoy to secret warehouses in the wider Los Angeles area.
On Christmas eve, after emptying his sleigh on the east coast, he flies across to Los Angeles to load up again.
GRINCH, it transpires, was intending to target the trains.
The word was they had stolen shoulder-held rocket launchers and intended attacking the convoy as it passed through Nevada just four days before Christmas. With the trains and toys destroyed, Santa would not have time to make fresh arrangements. There would be no toys for children up and down the west coast.
Santa knew there were few options. He could have moved the toys by air, but all planes at that time of the year were busy carrying people home for Christmas.
"What do the US authorities say?" asked Santa.
"They've promised to do their best," replied Terry, "but the western rangelands cover a huge area. Monitoring every kilometre of the railway line would be impossible."
Santa had few options but to call on his animal friends to help save Christmas.
"Not many," replied Terry. "But one thing is certain. The trains must get through. Otherwise, there will be no Christmas for millions of children!"
Santa sat down with senior staff from the US Department of Homeland Security.
"I'm sorry, Santa," said Ralph Matterson, who was head of Christmas intelligence. "As you well realise, there are millions of acres of rangelands in Nevada. If the GRINCH agents get in position a day or two early and hide under scrub to lie in wait for the train, we'll struggle to find them in such a vast area," he explained.
"We will do everything we can, but I'm afraid we cannot guarantee that we can protect your trains."
Santa's brow furrowed. "I understand," he replied. "Anything you can do would be appreciated."
The grand old man could not hide his disappointment. He knew he had only one choice. He got the word out to his animal friends. Perhaps they could help, he thought.
The animals met under cover of darkness 10 days before Christmas. It was a far-from-happy affair.
The brown and grizzly bears explained that they were unable to help. "We're pretty scary, but I'm afraid there simply aren't enough of us make a difference, and we couldn't get bears into position in time," said their spokesman, Bruno.
The big cats told a similar story. "We're too few in number to cover the desert and find them," John Cougar said. "We would be more than happy to help, but we simply cannot cover all that country and find where they're hiding out."
The birds of prey were similarly downbeat. "We stand a better chance of perhaps spotting them, but if they move at night we'll not stand much hope," said Eddie the Eagle. "Again, we'll help where we can."
Comanche was the last animal to speak at Santa's meeting.
Comanche, the horse representative, had stood in silence throughout the meeting.
He finally spoke.
"I believe we can help," he said.
The carnivores were taken aback.
Eddie the Eagle was bold enough to ask what all the other animals were thinking: How could a bunch of herbivores help out against Christmas villains armed with rocket launchers?
"We have the numbers," he replied. "And we have the horsepower. Rest assured, we will do our best."
It's a well known fact that nothing moves in the western desert without the wild horses knowing about it.
Word was put out across the range to watch for any suspicious activity and, sure enough, six days before Christmas, word reached Comanche of three men who drove into the desert by night, covered their black V8 pickup with scrub, and set up camp.
The location was Snake Valley, a remote part of central Nevada through which the main railway line headed east-west.
Killjoy had driven deep into the desert in the depth of night with two accomplices, each armed with a rocket-launcher and enough food for a week.
By daybreak, the vehicle was well hidden beneath scrub and their campsite well camouflaged. There was no way they were going to give their position away to any spy satellites.
Killjoy was a wanted man in 14 countries. His efforts to ruin Christmas made him an international fugitive.
His partners in crime were just as bad. Douglas Fir and Nicolas Sleigh had tried for years to ruin Christmas. This year they were adamant. Nothing would stop them.
Killjoy and his accomplices could occasionally see wild horses moving across the valley.
The country was as remote as any you could find in the western rangelands.
Occasionally, a wild horse or two could be seen wandering across the valley and a pair even came quite close to their campsite, apparently curious about what three men could be doing camping in the middle of nowhere.
On the morning of December 18, Killjoy's radio crackled into life. It was his operative in New York. Santa's convoy had rolled out of the city bound for Los Angeles.
Noel Yuletide eased the throttle forward and the lead train slowly accelerated along the tracks. It was a massive load, but with all the railway companies across the US on board, it should be a trouble-free journey.
All going well, he expected to be rolling into Los Angeles on December 23, just in time for Santa's magical Christmas Eve run.
Soon, New York City gave way to countryside and Yuletide eased open the throttle some more. The four other trains in convoy, spaced a mile apart, kept pace.
Santa's secretive Christmas convoy was on the move.
Killjoy did his calculations. The train, he was told by radio, had left at 8am. On his reckoning, it should be heading through central Nevada around the middle of December 21.
Unusual horse movements in Nevada were unable to be investigated until after Christmas.
"Federal authorities would put up a helicopter to check out the situation," the newspaper reported, "but the operation would not take place until after Christmas."
"It has been a particularly dry winter so far," the newspaper quoted a Nevada spokesman for the Bureau of Land Management, which is responsible for the wild horses.
"It's possible some of them are having to range further to find water, but we won't know more until after Christmas, when we'll get a helicopter up to take a look."
December 21 dawned with a clear sky, the sun quickly taking the icy chill off the desert night air.
Killjoy hauled himself from his sleeping bag and surveyed the scene. Beyond the tracks, the sun was sparkling off the ridge line on the other side of the valley. Today, he thought, would be a good day.
Santa would at last get his comeuppance.
Santa's rail convoy crossed the Nevada state line shortly after 8am, making good time on its journey east. Noel Yuletide looked at his watch and surveyed his map. All going well, the train should be in central Nevada in about two hours, and then onward to California. On his estimates, they should be in Los Angeles right on time.
The screech of an eagle overhead caught Killjoy's attention.
Come 9am, they were in position with their rocket launchers in hand. It was only a matter of time.
Killjoy looked skyward. An eagle was circling high overhead. It screeched three times, the noise echoing across the valley.
Killjoy's eye was suddenly caught by a movement on the ridge across the valley, to the north. He grabbed his field glasses and focused. Half a dozen wild horses had ventured on to the ridgeline and appeared to be looking in his direction.
In the corner of his field of vision he spied another horse, then another, then another! Before long he was scanning a ridgeline with what looked to be three or four thousand wild horses.
"What on earth is going on?" he exclaimed. "I've never seen anything like it."
His accomplices had no answers.
At that moment, the horses began wandering off the ridge and, once on the valley floor, broke into a trot. They were headed across the valley and straight towards their position.
"They must be migrating or something," Killjoy said. "We can't let them get in our way."
"Not a problem," said Douglas Fir, stroking his beard. "Horses are pretty timid. We'll fire a couple of rockets over their heads and that should scatter them."
The horses had crossed the railway line by now and had increased their pace to a gallop. Killjoy took careful aim at the centre of the line and fired a rocket just over their heads.
The rocket roared only a few metres above the horses and exploded with a mighty roar behind them. At that, the horses split in two, peeling off to the east and west, giving Killjoy and his accomplices a clear view of the track.
"That should do it," he said, eyeing the horses as they headed for each end of the valley. "That will be last we see of them."
The horses, however, had other ideas. As they approached the ends of valley they wheeled around and began thundering back across the valley floor.
Killjoy could not fathom what was going on. A mile or so in front of him the two groups of horses crossed and continued across the valley, their hooves kicking up dust, which hung in the morning air.
Again, at the ends of the valley the horses turned, thundering back across the canyon.
The horses turned and thundered back across the valley.
It was 11am, and the hills of Snake Valley had just loomed into view as train driver Noel Yuletide sipped on his morning coffee. His radio crackled to life on a special encrypted frequency.
The channel was used only in emergencies and was reserved for special messages from Christmas Inc.
He could hardly believe his ears. It was Santa himself, and the message could not have been clearer.
"I have no time to explain," Santa exclaimed. "Open your throttles and push on to LA as fast as you possibly can," he told his drivers.
Yuletide had no idea what was going on but knew he had to act. He leaned over and pushed the throttle hard forward.
The diesel-electric locomotive engine groaned under the strain as the train slowly gathered speed. Yuletide could hear the hastening clitter-clatter of the track beneath him. He was now going as fast as he felt he safely could.
Just ahead lay the entrance to Snake Valley. He could make out some sort of haze ahead, but strained to see exactly what it was.
The horses had just completed their fourth crossing of the valley floor. With each crossing, the dust which flew from their hooves continued to gather in the air. It climbed skyward and hung almost motionless.
Killjoy and his men could no longer see the tracks. They could see nothing. The dust cloud was hanging across the valley, obscuring everything.
Killjoy roared at his men to keep their eyes peeled for a glimpse of the tracks, but it was hopeless. The dust was now so thick they could barely see 100 feet in front of them.
From the eastern end of the valley he heard the unmistakeable sound of a train whistle. In fury, he fired off a rocket into the dust cloud, but it roared harmlessly above the horses' heads and into the ridge across the valley.
Yuletide was puzzled by the dust storm which appeared to have come up in the absence of wind as he entered Snake Valley. What could be going on?
The dust was now so thick Killjoy could barely see 100 feet ahead.
To his left, through the thick dust, he spied a large herd of horses. Could they be responsible for the dust? Surely not!
The dust storm cleared as quickly as it had begun as the train convoy exited Snake Valley and charged on towards LA.
"I can't understand the rush," Yuletide thought, "but if Santa wants us there in double-quick time, we've got to do it."
Killjoy was purple with rage. He and his men threw the scrub off their truck and loaded their weapons in the back. They set off in pursuit of the convoy, but the dust made the going very slow out of Snake Valley.
Even in clear air, they simply could not match the trains for speed across the desert, and the nearest decent road was 40 miles away. It took them 90 minutes to reach the sealed road.
Two hours later, they were on the interstate highway and chasing the train hard.
The rail convoy raced across the state border into California mid-afternoon, the temperature gauge on Yuletide's train pushing dangerously toward the red zone.
The Department of Homeland Security had picked up the mysterious dust storm on satellite and had sent agents to investigate.
As soon as Killjoy and his men broke cover in their pickup truck, specialist high-tech equipment had picked them up from the air.
Such was Killjoy's fury, he had let his guard down.
As Killjoy gunned along the interstate towards California, the unmistakeable sound of a helicopter filled the cab. He glanced skyward and saw two black gunships keeping pace with his truck.
He rounded the next bend to face an impenetrable road block. One of the helicopters swung in behind him, cutting off any possible escape.
Killjoy was done.
He emerged from his truck, arms high in the air.
Yuletide rolled the lead train into Los Angeles four hours ahead of schedule. Crews immediately began unloading the toys into massive warehouses. His job was done.
Santa learned within minutes that his convoy was safely through and phoned Yuletide on his cellphone to thank him for his efforts.
"I cannot thank you enough," said Santa, the relief obvious in his voice.
It was 1am on Christmas Day. Hundreds of wild horses were still making their way back to their home patches. The moon was shining brightly to light their way.
For a moment, the stars appeared to sparkle brighter and the horses looked skyward. A streak of light shot west across the sky.
It was Santa.
Such is the magic of Christmas, it was only a matter of seconds later that the massive warehouses in Los Angeles were emptied of toys and Santa's heavily laden sleigh set off to deliver gifts to children along the US western seaboard.
High above California, the grand old man smiled broadly as he looked east to view the magnificent open rangelands of Nevada, home to his very good friends, the wild horses.
"Merry Christmas, my friends."