One acquiring a following these days is Festivus:
Festivus, a well-celebrated parody, has become a secular holiday celebrated on December 23 that serves as an alternative to participating in the pressures and commercialism of the Christmas season. Originally a family tradition of scriptwriter Dan O'Keefe, who worked on the American sitcom Seinfeld, the holiday entered popular culture after it was made the focus of a 1997 episode of the program. The holiday's celebration, as it was shown on Seinfeld, includes a Festivus dinner, an unadorned aluminum Festivus pole, practices such as the "Airing of Grievances" and "Feats of Strength," and the labeling of easily explainable events as "Festivus miracles."
The episode refers to it as "a Festivus for the rest of us", referencing its non-commercial aspect. The English word festive derives from Latin "festivus", which in turn derives from festus "joyous; holiday, feast day".
(Xmas has been used for hundreds of years in religious writing, where the X represents a Greek chi, the first letter of Χριστος, Christ.)