The term SITCOM ALIEN refers to two popular characters from two different television sitcoms. ALF is a 3-letter acronym for the character Alien Life Form, who was the main character of the 1980s sitcom ALF. MORK is a 4-letter acronym for the character Mork from Ork, who was the main character of the 1970s sitcom Mork & Mindy. Both characters were aliens from outer space who lived on Earth and interacted with humans.