What can attack you in vanilla Minecraft?

Answer 1

Spiders (only attack at night), Endermen (if you look at them and they will die when it rains), Skeletons(if you get too close and they burn up at daylight), Zombies (if you get too close, and they burn up at daylight), Creepers (if you get too close and they do the most damage of any mobs) and you can actually out run them all.

Be aware though, Zombies and Skeletons will not die in daylight if they stand under trees, ledges, stand in water, etc.

If you attack wolves they will attack you if I remember right or if you accidentally hit some one else's tame wolf it will attack you.