Whichever "timed action", I always sucked at them, since early arcades era.
Suffering stat damaging attacks.
And losing savegames.
The aforementioned things I fear and hate.

There's a fear that I don't hate, being ambushed by strong creatures in dungeons, I remember jumping on the chair when I bumped into ghouls and wraiths behind a corner or a door in AD&D Treasure of Tarmin on the Intellivision: when it scares me, it's because the game is good and it has the right atmosphere, while I don't fear, but I hate, when a foe is scary because badly balanced, too strong for my character's maximum possible stats when I meet it and the challenge becomes trying again until I casually succeed.

Having to replay a part of the game. I save after every killed enemy.

Glitches that cause unfair deaths...over and over.

Campers, hard jrpgs.

Deathclaw Sanctuary

Dying against a boss in Lost Odyssey after I have just spend the last 2 hours *trying* to grind.

Also, there's always the:

*game freezes*.
"WTF is going on?"
*Turns console on to three Red Lights of Death*.
"NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!"
*Runs to VGC and makes hate thread*.

you have a 6 killstreak in CoD4/5, and some camper kills you

Being far ahead in a game and getting into a state where you can't progress.

Also, being far ahead and making the wrong choice in a game and saving and not being able to go back without redoing the entire game.

Those are my worst.

That when I go to "Load Game" it tells me that my save file is deleted/corrupted.