Santa Bot was created by the Momcorp subsidary Mom's Friendly Robot Co. to determine who had been naughty and nice, and distribute presents accordingly. Unfortunately, Santa's standards were set too high and he invariably finds everyone to be naughty (except Dr. Zoidberg). He then stalks the streets, hunting down the naughty people and kicking some naughty ass with his arsenal of high-powered weaponry. In the future everyone stays inside after sundown on Xmas Eve unless they have a death wish, as the suicide booths all have long queues at that time of the year.
In the year 3000, Santa Bot was foiled in his dastardly plans by the Planet Express crew, though he vowed to come back when they least expected it (next Xmas).
The following year, Bender had to take Santa Bot's place after he was frozen by the aformentioned Planet Express crew. Unfortunately, the people of Earth were not aware that the new Santa was a friendly robot, and Bender had a hard time staying out of trouble.