People who played Aliens on "Stargate SG-1".

   7.9  

Name: Teal'c
Race: Jaffa
Home Planet: Chulak

He is an all-time veteran member of SG-1.

So all 10 seasons.

CharlieBlue's rating:

   4.3  

Name: Major General Jacob Carter/Selmak
Race: Earthling (Tau'ri)/Tok'ra
Home Planet: Earth/Unknown

"Jacob" is also the father of "Captain/Major/Lt Colonel/Colonel Samantha 'Sam' Carter," all-time veteran member of SG-1.

Seasons 2-8.

CharlieBlue's rating:

   6.5  

Name: Master Bra'tac
Race: Jaffa
Home Planet: Unknown

He was the mentor, teacher & friend of "Teal'c."

All 10 seasons.

CharlieBlue's rating:

   8.4  

Name: Vala Mal Doran.
Race: Human/Former Goa'uld Queen Qetesh
Home Planet: Unknown.

Became a member of SG-1 very late in season 10.

Else appeared in one episode of season 8 and some episodes of season 9.

CharlieBlue's rating:

   8.3  

Name: Ba'al
Race: Goa'uld System Lord
Home Planet: Unknown

Appeared in 15 episodes from season 5-10.

CharlieBlue's rating:

   8  

Name: Cassandra (Later adopted by "Dr. Janet Fraiser")
Race: Human
Home Planet: Hanka

Katie played "Cassandra" for two episodes:
"Singularity" in season 1 + "In the Line of Duty" in season 2.

CharlieBlue's rating:

   0  

Name: Cassandra
Race: Human
Home Planet: Hanka

Colleen took over for Katie, in playing "Cassandra" for one episode, in the fifth seasons "Rite Of Passage".

However Colleen played "Ally", in second seasons "Bane". "Ally" was all Earth human.

   7  

Name: Skaara/Klorel
Race: Human/Goa'uld
Home Planet: Abydos/Unknown

Alexis replaced his role as "Skaara" from the original "Stargate" movie, once the TV show was a reality.

Appeared in 5 episodes, stretching from season 1-6.

   5.5  

Name: Kasuf
Race: Human
Home Planet: Abydos

Erick replaced his role as "Kasuf" from the original "Stargate" movie, once the TV show was a reality.

Appeared in 3 episodes from season 1-4.

   0  

Name: Rya'c
Race: Jaffa
Home Planet: Chulak

"Ray'c" is the son of "Teal'c".

Appeared in 6 episodes from season 1-8.

   7.5  

Name: Jonas Quinn
Race: Human
Home Planet: Kelowna

He temporarily replaced Daniel Jackson, on SG-1, when Daniel Died and ascended, after a radiation mishap on Kelowna.

Were on for 26 episodes from season 5's "Meridian", all of season 6 and season 7's "Fallen", "Homecoming" and "Fall Out."

CharlieBlue's rating:

   5.8  

Name: Gerak
Race: Jaffa
Home Planet: Unknown

A powerful and influential Jaffa, Gerak is the first leader of the new Free Jaffa Nation. He was formerly the First Prime of Montu, a minor Goa'uld who once served Ra and later fell in with Baal when Ra was killed.
(Borrowed from "GateWorld," because I couldn't get my own words to even sound coherent enough.)

Episodes:
Origin pt. 3 (Season 9, episode 3, 2005)
Beachhead (Season 9, episode 6, 2005)
Ex Deus Machina (Season 9, episode 7, 2005)
The Fourth Horseman: Part 1 (Season 9, episode 10, 2005)
The Fourth Horseman: Part 2 (Season 9, episode 11, 2005)

CharlieBlue's rating: