TNTSheep

TNTSheep is an exaggerated copy of Sheep. The mob first appeared in the TNTSheep mod.

Obviously, the TNTSheep has the same texture as TNT and a sheep. The only notable difference is that there is a block of TNT in the middle of the sheep.

Behavior
TNTSheep normally don't do any hostile behavior. Though the idea may seem similar to a creeper, it does not come near you. But, sometimes it might be near you and if it's on the range of exploding, you might want to walk away. It explodes about the amount of blocks as normal TNT, and will spawn in a 1 out 5 % chance of a regular sheep.

Sometimes, Baby TNTSheep will spawn and it will give less of a chance of exploding.

Credits
Credits go to Jamie1051FTW on Minecraft Forums.