A lot of votes for best nickname. How about worst ones? One of our dipshit announcers in AZ last season called our closer Jose Valverde "Papa Grande". He's a big guy so he was thinking "Big Daddy". However it translates as "Big Potato" Jose says he likes it but I think he's just being nice.

These may not be great, but they just fit:

Hakeem - "The Dream"
Oliver Miller - The Big O
Dennis Rodman - The Worm
Domminique Wilkins - The Human Highlight Reel
Charles Barkley - The Round Mound of Basketball

In San Antonio the local paper had a story on Tim Duncan his rookie year, about him wanting to be called Merlin, it didn't stick.
Tim Duncan - The Big Fundamental (who can't hit freethrows, go figure)

Mr Hockey- Gordie Howe
Mr Zero- Terry Sawchuck
Bret "the hitman" Hart (had to throw that in because hes the only wrestler I liked)

that is such a ripoff of the Cowboys' Daryl "Moose" Johnston's nickname... where even in the opposing team's stadiums, it became tradition to yell "Mooooooooose!!!" whenever he first touched the ball.

I have always liked "shoeless" Joe Jackson
and "Mr.October" Reggie Jackson

I think the worst is PUDGE .......sounds like a 3rd rate Porno Actor.

I personally like "The big hurt" for Frank Thomas. Simple, powerful, true.

I'm watching the Lakers/Pistons game 4 and if I hear "The BIg Aristotle" again I think I'm gonna puke!

that picture that monkeydriven posted means nothong to me but I am assuming by reading a previous post that it shows Dieon Sanders. Was he the one that played baseball as well?

I always liked Drexler's nickname and Earl "nanny goat" Manigault.
Saw the film about Manigault's life and he had a truly incredible vertical before he f*cked his body up.

I am an Atlanta Hawks fan, since someone already covered Doninique, how about

The Plastic Man- Stacy Augmon

He is tall, lanky, agile, and earned the nickname in his younger years.

Bad Nickname

Shaq of the Mac- Gary Trent

Two reasons why its an awful nickname. First, if you have to use someone else name in your nickname, thats sad. Secondly, he has not got close to Shaq's level, and whenever he makes a good play in a game, some announcer always brings up that damn nickname.

I am not a Nascar fan, but I didn't see where anyone mentioned the Intimidator?

I also like the Big Unit. How lucky are you to get that nickname?

Anybody named Deuce. Most recently Deuce McAlister, but before that I was yelling "Deuce" for Deuce Staley of the Gamecocks.

I once had the nickname of Deuce when I went to ITT. When I walked in the room, my friends (all 30+, and I was 18) would yell out "DEUCE!!" Don't ask me how that came to be.

Tony Kukoc - The Croatian Donation.
Who can forget Wilt "The Stilt" Chamberlain?
Ozzy Smith - The Wizard of Oz

"Space Man" Bill Lee

One of the great Red Sox players of the the 1970's who, aside from Doc Ellis of the Pirates, admitted pitching while completely tripping on LSD. Most of the time, though, he was just stoned.

Of those not yet mentioned:

El Caballo - Carlos Lee
K-Rod - Francisco Rodriguez

Of those mentioned:
The Rocket
Big Unit
The Great One

And the best nickname ever:
Sweetness