The OP asked for female action stars, the statement was made “This discussion only needs one name and it’s Sigourney Weaver.” That statement found support, “True. Close the thread already.” I disagreed; pointing out that Mrs. Weaver wasn’t the first or last name in the female action star field. Mrs. Grier’s films may not be quality but I consider them “action”. They were made during a time when there weren’t many action roles for women.
I wasn’t aware the quality of the film was at issue. The OP asked for female action stars. I remember Mrs. Grier and her films because it was the first time I saw an attractive black woman kick butt on the big screen.
The OP asked for the greatest female action star. The quality of the films must surely be one criterion for that. Grier might have been before Weaver chronologically, but I think it’s a huge stretch to say that she’s greater.
The title of the thread is Greatest. I like Pam Grier and her movies clearly as I have seen so many but her movies were pretty bad sadly and Alien and Aliens and Galaxy Quest were all great movies with Weaver in an action role.
Ripley is so far above anyone else I can classify as a “female action hero” I will have to give it to Weaver. (heh) Just before Linda Hamilton in T2.
But Pam Grier certainly deserves a place somewhere high on the list just because she did SO MANY action movies - and some of them are actually good. I’m sure quite a few 70’s Asian kung fu women should be here too, but I just don’t watch enough kun fu movies to remember any of them.
Peta Wilson.
The scene in Nikita, “Falling Star” where she kills the redneck woman with her bare hands and she and Michael, handcuffed, team the 12 gauge to kill all the bad guys is outstanding.
Beauty and the Beast was a romance, but some serious ass-kickin’ did take place. Plus, Ron Perlman never looked better.
To say that GQ (as fun as it is) is an “action role” for Weaver is being exceedingly generous, given her only job on the ship is a running joke in the first place. She never holds a gun, operates a vehicle, or performs a stunt in the entire film!
Compared to whom, Piltdown Man?
Why not let a poll decide the issues here?
Which is why I specified “memorable”. 
Sure, I left it open for a couple of days to see what the nominees will be.
I’m going with Michelle Yeoh - she gets much credit for actually doing the action in her action movies and she’s remarkably graceful about it. Watch some of her early HK action films, not the mediocre Hollywood stuff that many Asian stars got put into when people began paying attention to them in the US.
We’re talking about a woman who jumped a motorcycle onto a moving train. No stunt double, no wires, no CGI.
I think there’s a lot more to being an action movie star than grimacing fiercely in an action movie while doubles, poor lighting, special effects and too many fast cuts do all the real work.
Joanna Lumley’s character ‘Purdey’ in the seventies UK series “The New Avengers” would fit the bill.
As a fourteen year old, it was always a toss up between her and Farrah Fawcett…
Compared to Ron Perlman, of course.
I hate having to explain jokes.
In addition to Michelle Yeoh, I’d throw in Zhang Ziyi from Crouching Tiger & the House of Flying Daggers.
Obligatory link. And then of course, there’s this (to pick a fairly well-known example).
How about Maggie Q?
It just occurred to me that nobody’s mentioned Carrie Fisher yet. And yes, I would consider Princess Leia an action character: For starters, she’s the only character in all eight movies who ever demonstrated an ability to shoot what she was aiming at.
By the same token, Natalie Portman also qualifies, but I like Leia better than Amidala.
Though she couldn’t hit for shit in Blues Brothers but I will assume she did not really want to hit.