Diablo 2 ( Over 10 years of playing )
Maple story ( 6 years of playing )

World of Warcraft
Counter-Strike
Diablo 2 (was level 99 for like 4-5 ladders in a row, once was #1 paladin US East ladder).
Final Fantasy series.
Runescape
Pokemon(mostly red/blue/gold)

Might not be 1000 hours but they are def over 500 hours.

World of warcraft hands down, we're not talking about hours, we're talking about months, years even.

Diablo 2
Runescape
Final Fantasy
League of Legends.

Pokémon (Red, Yellow, a little Silver, Stadium, a little Snap)
FIFA
Counter-Strike
Diablo II
Warcraft (especially WC3 custom maps, not DotA though)
Tekken (mostly 1-4)
Mario (NES+SNES, 64, Kart, Smash Brothers)
GTA (mostly the third, didn't like the 2D ones that much)
Unreal
Quake

Maybe Runescape, but it's probably 'only' about 500.

There are probably loads I don't remember.

EDIT: Knew it, the Harry Potter games! Especially played the first one, probably 10 times through on Playstation.

This post was edited by KrQl on Nov 5 2012 08:45am

D2
pokémon
Final Fantasy
Age of Empires 2
DotA

D2
Pokemon
Final Fantasy
Super Smash Bros. Melee (Played this way too much)

Diablo 2
Counter Strike 1.6

This + Gta VC

starcraft/ broodwar
runescape
final fantasy
pokemon

almost 5k hours into Guild Wars
about...3k hours into WoW

I'd estimate atleast 1k on Halo 2 as well