Captain Jean-Luc Picard is absolutely, without a doubt, the greatest Science Fiction character ever to walk the face of a Starship. His ability to comprehend the complete abstractness of the Q Continuum is terrific :P and he's just a cool guy. Also, Patrick Stewart is one of my favorite actors.

It would be far to difficult to narrow my selections down to only one character, so I'll narrow it down to three (or try to at least). These are in no particular order so read them as a tie.

Jack O'Neill, he's witty subtle and always saves the day in the end. I'm not sure what else to say, if you've ever watched Stargate SG-1 (and if you haven't you really should...) you know why Jack makes my short list.

Lee "Apollo" Adama, always does the right thing. In fact in a series where Murphy's Law has gone into overdrive, and almost every character has been forced to adjust their moral compass Lee is stubbornly idealistic. To top it off he's not a half bad pilot when push comes to shove.

Han Solo, the original space cowboy. He's a trigger happy, brave, and as loyal as a wookie. The man is a walking improbability, luck and chance have no power over him: just look at the number of times supposedly crack shots inexplicably miss him.

Honorable mentions include Jean-Luc Picard, Malcolm Reynolds (certainly the more literal "space cowboy"), Rodney McKay, Daniel Jackson, William Adama, Galen Tyrol, and many others. Ask me again in a few days and I'll probably rotate people out of the "best" list and add more to the "honorable mentions."

It would have to be Flash Gordon. He was the pioneer of sic-fi entertainment.