Santa Claus Conquers the Martians

From Wikipedia:

Santa Claus Conquers the Martians (also titled Santa Claus Defeats the Aliens) is a 1964 science fiction film that regularly appears on lists of the worst films ever made. It is regularly featured in the "bottom 100" list on the Internet Movie Database. It was directed by Nicholas Webster, and it stars John Call as Santa Claus. It also includes an 8-year-old Pia Zadora playing the role of one of the Martian children.