3rd Rock from the Sun - Season 6 - Eps 19: The Thing That Wouldn't Die (1)
Mary is having trouble dealing with what she has just seen - Dick transforming Liam into a monkey, which he had done to stop him doing the same to the Earth's population. Dick consults the other Solomons and they decide that the best approach is to deny everything. Meanwhile, Mary meets with Nina and Judith, who confess that they believe Dick to be an international terrorist, so when Dick and Mary next meet, she demands that he tell her the truth about himself. So, Dick tells Mary that he and the others are aliens. Mary's reaction is first disbelief, then shock, and then she finds it sexy to be dating a spaceman. Elsewhere, the local store has been robbed and Sally catches Don hiding in the frozen foods freezer, where he admits that he hid because he was scared. Harry takes a different line and asks the shopkeeper Sam out on a date, but later runs into her working at a posh restaurant, where she instructs him to call her Samantha. Confused, Harry believes that he is dating twins.
About 3rd Rock from the Sun

Title: 3rd Rock from the Sun
First Air Date: 1996-01-09
Last Air Date: 2001-05-22
Status: Ended
Rating: 7.5/10 (from 503 votes)
Language: EN
Seasons: 6
Total Episodes: 139
Network: NBC
Genres: Family, Sci-Fi & Fantasy, Comedy, Drama
Production Companies: Carsey-Werner Company
Synopsis
The high commander of an alien expedition lands on Earth -- what he considers to be the least-important planet -- in human form as Dick Solomon. Along for the ride are his alien compatriots Harry, Sally and Tommy -- who is the eldest of the group but is now angrily trapped in a teen's body.
Cast

John Lithgow
Dick Solomon

Kristen Johnston
Sally Solomon

Jane Curtin
Mary Albright

Joseph Gordon-Levitt
Tommy Solomon

Elmarie Wendel
Mamie Dubcek

French Stewart
Harry Solomon

Simbi Khali
Nina Campbell

Wayne Knight
Don Orville