Halo
Fallout
Fable
Ninja Gaiden
BioShock
Oblivion
Castlevania

Anything Mario

Zelda

zelda

Kingdom Hearts II (the first one is so much better)
LittleBigPlanet
Any non Mario Kart racing game.

halo
gears of war
BioShock
Oblivion
Fallout

Halo.
CoD.
Gears.
GTA
Wii Everything.
Singstar.

Damn, 5 votes for Oblivion.

Well, at least it looks like everyone agrees that Oblivion is a very popular game that most people like. ^^

Wow I see alot of great games I can't phantom how anyone could dislike

Mainly

Fallout 3
Mass Effect
Halo
GTA
Guitar Hero
and Rockband

well i dont dislike but i feel these games are a bit overrated

Fallout 3
GTA IV

There's a fair chunk for me, actually. So I'm going to go by franchise, rather than each title, unless it's only part, when I will clarifiy which I don't like.

GTA: It's not that I object to violence, persay, but rather, the way that this game constantly pushes the envelope and gets... unwanted attention toward video games, that has made me hate it so. Oh, and sandbox games really have to strike the right chord with me, and this series doesn't.
Halo/Killzone/(insert FPS series here): I never really cared for FPSs. (Well, check that. Something in me liked Goldeneye under certain rule settings...) I use things like peripheral vision when I do stuff like that, but the TV just limits me.
Final Fantasy 7+: The first 6 were great games. Square sold out to the mainstream and graphics for 7, and never looked back. And as time went on, the stories seem to have also gone to the crapper, which is also where the challenge went. It's one of the reasons that I worry about every new DQ game that's announced...
Metroid Prime: Get your FPS out of my Metroid!! The exploration was severely limited from prior ones. I remember the first time I played the first one, and how I loved getting lost. The worlds are too restrictive now to just wander around aimlessly.
3D Zelda: Ironically, it was Ocarina of Time that turned me off from these. Yes, I beat it, but it was painfully easy. There doesn't seem to be as much hidden stuff, and what is hidden, isn't hidden well. (Without any guide, I'm only missing a handful of skulltullas.) And Majora's Mask felt like more of the same, to the point where I didn't bother finishing it. I still can't tell you where every secret in Zelda 1 is, and that's how I like it!

I'm sure there's a lot more, but I don't feel like spending forever typing them up...