The John Lithgow-led comedy about a quartet of aliens living in disguise on Earth in order to observe human life is definitely one of the most memorable comedies of the '90s. The tongue-in-cheek humour and blending of sci-fi with classic sitcom tropes made it a critical success, even if its ratings were typically more middling. While it hasn't always aged gracefully — like most '90s sitcoms — it's still a memorable and hilarious show that's worth a rewatch. Plus: young Joseph Gordon-Levitt!