Santa Claus is a character that appears in the special missions of Christmas events. This character appears first Christmas event in 2009 and also appeared in the 2010 ChristmasEvent.
Missions that appears
In Christmas 2009 event:
Christmas's Gift. (Christmas 2009)
Counterfeit Christmas Father !?. (Christmas 2009)
In Christmas 2010 event:
X'mas Ninja Claus