Great point on Kessler, that was an epic bossfight. From the standpoint of a player trying to get the best of him, memorizing his moves and responding to them brought me back to the Mega Man days. inFamous was one of my favorite games from last year, I hope Sony's got that sequel coming sooner rather than later.

The Leviathan from Resistance 2 was pretty astonishing. Seeing it at Sony's E3 was something else and I'm glad I wasn't let down when I actually got to play it. Although from a gameplay perspective the boss at the end of the Twin Falls, Idaho mission might be better. One of my favorite aspects of Resistance 2 is that it's one of the few FPS games I've really seen implement boss fights, and well.

Of course I wouldn't be in these forums if I didn't say:

Gilgamesh!!!

All of the above are pretty great, but for GREATEST boss fight ever:

Metal Gear Solid 3's final, ahem, boss. Probably the intersecting line of how effective a boss fight can be emotionally and from a gameplay standpoint at the same time.

Crying Wolf from MGS4. They took "The End" fight from MGS3, universally considered one of the greatest boss fights of all time. Then they combined it with the alternate "The End" fight where an entire unit of enemies is actively searching for you on a giant map.

And then they put it in the middle of a snowstorm. It's one of the most memorable "moments" I've had as a PS3 owner, and having beat it without being spotted is one of my personal accomplishments in gaming.

The End is a boss fight I have to say by default because of the above. Arguably better than Crying Wolf, and having actually snuck up on The End instead of the other way around is one of my other accomplishments in gaming (although it gets relatively easy once you get the hang of it).

I think as a whole the Metal Gear (Solid) series dominates any reasonable list of best bosses in gaming, and I'm glad MGS4 was no exception.