Chicken attacks in Zelda games are definitely among my dumbest deaths. 

In CoD modern warfare 1, I was trying for an achievement called "misery loves company" which meant you had to get a kill by overcooking a grenade.  Got a double kill + suicide after about 5 attempts.  And I'm pretty sure I wasn't the terrorist squad...

Playing GTA4 online and trying to hop into a military chopper that somebody was getting ready to take off in. The player pulled the chopper off the ground preventing me from getting in and then landed it right back onto me lol

Minecraft... I forgot the #1 rule to never dig straight down.
Hooray, a deep cave under me.
My house was pretty far from my death site, so I lost all my things.

in skyrim there is a spell which reduces health but adds magicka. when i used it i died for holding it too long

I was killed by a cougar in Red Dead Redemption.

I was trying to complete all the outfits and challenges. I believe I was doing a hunting challenge and I only needed to skin one more animal to complete on of the last challenges. I went to skin the animal and out of nowhere I could hear a cougar roaring. When I was done skinning the animal the cougar attacked me instantly killing me. I had to start the challenge all over again. >___

I died of Gluttony on he River Vid.

Glitching out of a game like MW3 while you're on a 23 kill streak...

In World of Warcraft in a battleground i used a spell that makes me to leap backwards, the leap was too big and i fell in a big hole.

In the same battleground i near dead but i managed to trick the enemies to ignore me using a spell named "Feign Death" and I tied to run on my mount, but an "over time damage" spell killed me.

before entering an other battle ground i forgot to dismount my flying griphon.when I leaved the battleground i was dismounted and fell on rock from 50+ yards and died

In halo 3 I used a man cannon to fly up level with the cockpit of my friend's banshee and shot it straight on with a rocket.  It was a perfect shot and I landed on the ground unharmed. The the cockpit hit me square in the face.

Mw3 I had a C4 stuck to a wall and a guy ran into the dome and saw my C4 so he threw a semtex and I blew up the C4 and we both somehow got a kill. he threw a semtex at the barrel. 2 kills away from a M.O.A.B :(