Top 3 Sci- Fi Actors

What are you favorit Sci-Fi Actor all time both Star Wars and non Star Wars

Star Wars
1 Harrison Ford (Han Solo)
2 James Earl Jones (Voice Darth Vader)
3 Natalie Portman (Padme Amidala)

Non Star Wars'
1Patrick Stewart (Jean- Luc Picard, Star Trek)
2 William Shatner (James T. Kirk, Star Trek)
3 David Tennant (Tenth Doctor, Doctor Who)

i will post later, i'm too busy thinking about natalie portman now

The main reason i have Portman the list is She is a talent and a Beautiful actress

Ooooo thats a toughie!

For acting ability in the films I think I'd go with these lot:

Star Wars:

1. Harrison Ford (Han Solo)
2. Sir Alec Guiness (Obi-Wan/Ben Kenobi)
3. Liam Neeson (Qui-Gon Jinn)

I'm a bit confused about the non-Star Wars ones so I'm going to leave them for the meantime. I can give you my fave at least though:

1. Sigourney Weaver (Ellen Ripley/Alien Quadirilogy).
2. Kurt Russell (McReady/The Thing) - Thanks for the reminder Godjera!!
3. Richard O'Brien (Mr. Hand/Dark City)

I'm assuming we're going on acting ability in Sci-Fi roles?

I'm going to have to agree with Sureshot for the 3 Star Wars performances.
As for outside Star Wars:
1. Patrick Stewart (JL Picard)
2. Kurt Russell (Snake Plissken - if you count the movie as Sci-Fi)
3. Arnie (The Terminator)

Star Wars:
1. Harrison Ford
2. Carrie Fisher
3. Mark Hamill

Non-Star Wars:
These are probably missing out fantastic performances from better actors but here's what comes to mind this morning!
1. Sigourney Weaver (Alien Quadrology)
2. Cillian Murphy (Sunshine/Batman/28 Days Later)
3. Summer Glau (Firefly & Serenity) or Claie Danes (Terminator 3)... Can't decide.