The "3rd Rock from the Sun" Cast

Name: Dick Solomon
Species: Extraterrestrial
Gender: Male (in human form)
Occupation: High Commander, Physics professor, Lawyer
Title: The High Commander

"OH MY GOD! I'M GORGEOUS!"

Name: Sally Solomon
Species: Extraterrestrial
Gender: Female (in human form)
Occupation: Security officer, Homemaker, Various short-lived jobs
Title: Lieutenant

Name: Harry Solomon
Species: Extraterrestrial
Gender: Male (in human form)
Occupation: Transmitter, Various short-lived jobs
Title: Harry (later promoted to Harold)

Name: Tommy Solomon
Species: Extraterrestrial
Gender: Male (in human form)
Occupation: Information officer, Student
Title: Information Officer

Name: Dr. Mary Albright
Species: Earthling
Gender: Female
Occupation: Anthropology professor
Title: Doctor of Philosophy

Name: Nina Campbell
Species: Earthling
Gender: Female
Occupation: Administrative assistant

Name: Mrs. Mamie Dubcek
Species: Earthling
Gender: Female

Name: Sergeant Don Orville
Species: Earthling
Gender: Male
Occupation: Police Officer
Title: Police Sergeant

Bug Pollone, one of Dick's students.

Leon, one of Dick's students, played by John Lithgow's oldest son.

Caryn, one of Dick's students.

Aubrey Pitman, one of Dick's students.

Dr. Judith Draper, professor at Pendelton and colleague of Mary.

August Leffler, Tommy's first girlfriend (in seasons 1–3, sparsely appears in seasons 3 and 4).

Alissa Strudwick, Tommy's second girlfriend (in seasons 4–6).

Dr. Vincent Strudwick, Alissa's father and rival to Dick (in seasons 2–6).

The Big Giant Head, The aliens' boss. He goes by the name Stone Philips on the Earth (in seasons 4 & 5).

Vicki Dubcek, Daughter of Ms. Dubcek, Harry's on-off girlfriend who ends up having a child with the Big Giant Head (in seasons 2–6).

Dr. Liam Neesam, a professor who briefly has a relationship with Mary, and is later revealed to be an evil alien (in seasons 3 & 6).