Santa is a member who joined the MFGG forums on December 8th, 2007 for the Secret Santa event in the General Chat. He does not seem to have any relation to NEGA-SANTA or POSI-SANTA, but is instead the real deal, devoted to bringing joy and presents to all.
The cooperation between Santa and MFGG, and Santa's subsequent administrative status, was originally orchestrated by Bacteriophage, Nova, and Grant, who otherwise have no relation to him. (They aren't even allowed to help wash the reindeer poop off of his sleigh.) Hatman also helped out during the first event.
Santa was once the only MFGGer with a Happy Heart Badge and a Super Happy Heart Badge at the same time, other than Atlas33 and for a period, Retriever II, but this was soon changed, and now he only has the SHH badge. However, it was found out that Santa was able to give out badges.
At the Horrifying Halloween Hallway event held on October 31, 2010, Santa was arrested after being falsely accused of murder, and was believed to be in jail. His job was taken over by Neo Santa for one year.
Santa is still his jolly self, and still hosts the yearly Secret Santa event every December. In each Secret Santa event as of 2014, Santa takes on a different form. In 2014, he was a DLC-delivering robot. On 2015, Santa was Mario from the Super Mario World cartoon who is somewhat dressed like Santa. And on 2016, Santa became a superhero and changed his name into Super Claus.