Just about any super hero is 6' or more.
Robots (like transformer, voltron, Iron Giant)
Grimace
Big Bird
Barney
Godzilla
Gamra
Any Titan
Zeus
Chewbacca
Young Frankenstein
Frankenstein
Creature from Black Lagoon
Hill Giant
Fire Giant
Stone Giant
Draconian
The Devil from the movie "Legend"
walking Tree
A Chair (I saw this done once where the guy dressed up as a reclining chair and sat in the room and waited for someone to sit on him then jump up and grab them. Very funny)
A building that turns into a robot (from the movie Big)
A Yeti
Hulk
Abomination
Red Hulk
Galacticus
I could go on but I won't lol
Sabertooth? Or dress as Gandalf and get some average size guys to be hobbits! I'm 6'4'' myself so I know how this can be an issue. FYI proportionately most manga characters are in the 6'5'' range.
If you are that tall and like to cosplay...do something that most others will find imposable, your biceps and thighs are longer than most. I specialize in large costumes and the one thing i cannot change is the length of my biceps/thighs. Stilts will cover the forelegs, and arm extensions will extend the forearm, but only someone who is BIG will be able to get the proportions right. Oh and if you want something truly awesome, then do something that has not been done before. Don't waste your height on anouther pred or darth, Thats all been done( and very well by some of the people right here ). good luck!
I wish i was that tall, i'd be able to go as one of my comic characters lol. chris Reeves was 6'5 so Superman for sure, a predator for sure, a ton of anime characters if you're into it.