Who would in a fight? Unlikely, but good matchups.

[The Animator]

Worf vs. Chewbacca

Chewie: "HRRAAARrrgggghhhhh!!"
Worf: "Umm, yeah.. I've changed my mind... today isn't really a good day to die. I'll er... I gotta go."

......

Kirk vs Malcolm Reynolds

Kirk: "MAAAAAAAAAALL!!!!!!"
Mal: "What in the verse is all that screaming for? Jane will you shoot him please?"
Jane: "Gladly."
Zoe: "Don't bother, I'll handle this."
Mal and Jane: "Ooooh hell."
Kirk: "Well hello Miss, I'm Captain James OOOWWWW!! Ow ow ow ow ow ow ow... oooowwweeee!"
Mal and Jane: "Ooooooooooo..."
River: "Oh look! Were on DU."

......

The 300 versus Kratos from God of War.

Leonidas: "Tonight we dine in HELL!!"
Kratos: "Oh I just got back from there, try the Minotaur Steak... very tasty.

......

Or T'Pol vs Seven of Nine

T'Pol: "Jello... wrestling?"
Seven: "And why are we wearing Bikinis?"
Arch: "We... uhh.. have to.. respect this planet's culture."
T'Pol: "This is your planet.."
Archer: "Exactly."
T'Pol: "Well, Okay."
Jane: "...I'll be in my bunk."

Batman vs. Boba Fett

Tasmanian Devil vs Stitch

Freddy Kruger vs Wolverine

Dexter vs Pinky and the Brain

Huey Dewey and Louie vs Wacko Yacko and Dot

All seven Dwarves vs the Goodfeathers

Predator vs Master Cheif

Darkseid vs Darth Vader

[DarkTirade]

1. I don't think Leonidas would do well outside of his element.

http://www.digitalpimponline.com/strips.php?title=movie&id=300

[Arkham House]

2. hmm...how about Joe McCarthy vs Huey Long...?

...my money would be on the Kingfish...

[Arkham House]

3. another one--Phoenix vs Q...

...my money's on Jeannie any day...

[The Animator]

4. Q vs Mister Mxyzptlk

VS

[Dr. Strange]

5. Just how sure are we...

that they are not in fact the same entity?

[TheMightyFavog]

6. How about Sweden vs. Finland. vs. Norway vs. Denmark?

My choice is Finland. This is the same country who kicked the Soviet Union's Ass in the 40s.