Annihalation on shotbow.
I get terrified when I sneak into my opponents base....

My scariest moment. I play on hardcore because the whole one life things makes me a) more careful and b) feel like it's a real life situation. Anyway, I was deep underground. As I was walking through my well-lit mine, I kept feeling like something was following me. I'm sure everyone knows that feeling. So every five minutes I would turn around only to find an empty hallway. I use a technique known as strip mining so I did 1x2 tunnels into the earth. Not the smartest idea considering that there's no way to quickly escape if I'm trapped. So. As I was digging, I found diamonds. I was like :D. I noticed that one of the ore blocks made up part of a small cavern. I heard a zombie so I knew there was one above me. As I was about to mine my way up into the cavern, the zombie dropped down into the hole I made. He couldn't reach me because a block was keeping him from walking into my mine. Anyway, as I was about to penetrate into this cavern, the zombie fell down this hole and dealt damage to me. I jumped out of my skin...

Well I was in survival singleplayer and it was my first time playing minecraft and I was mining iron and a creeper was behind me I turned around and literaly said "OMG ITS A GREEN THING." then it exploded me and I started raging. :3

Mine is, i found a cave near my epic house (i have no screencaps, sorry) then i was exploring it, and i found diamonds, i mined them, and got so happy i didn't pay atention, aaaaand i fell in lava, either that or my first enderman encounter

Back in Beta, I saw a zombie, got scared thinking it was Herobrine, but of course, he is just a hoax.

I was mining, heard a sound, was like" Whats that! I'm on peacful right?" so I turn a corner, and there was a...
bat.
I shreiked so loud and fell back in my chair XD