Hey Arnold! - Arnold's Christmas (S2 Ep11)

Merry Christmas, Mr. Bean

Rugrats - Chanukah (S4 Ep1) Not Christmas, but it's one of the very best Holiday episodes

Batman: TAS - Christmas with the Joker / Holiday Knights

The X-Files – How The Ghosts Stole Christmas (S6 Ep6)

Justice League - Comfort and Joy

King of the Hill - Livin' on Reds, Vitamin C and Propane (S8 Ep7)

LOST - The Constant

Barney Miller - A Christmas Story

All the Doctor Who Christmas Specials (except the Peter Capaldi one with the Superhero)

Most of the Frasier Christmas episodes too

Bottom - Holy

Home Improvement – ‘Twas The Flight Before Christmas

Cheers - Christmas Cheers