Have you never read the Three Billy Goats Gruff? The version with pictures is very popular. http://en.wikipedia.org/wiki/Three_Billy_Goats_Gruff
The story introduces three male goats, sometimes identified in the story as youngster, father and grandfather, but more often described as brothers. There is no grass left for them to eat near to where they live, so they must cross a river to get to a "sæter" (a meadow) or hillside on the other side of a stream in order to eat and get fat. To do so, they must first cross a bridge, under which lives a fearsome troll who eats anyone who passes that way. The smallest billy goat is the first to cross and is immediately stopped by the troll who threatens to "gobble him up!" The little goat convinces him to wait for the bigger billy goat to come across because he is larger and more gratifying as a feast. The greedy troll agrees and lets the smallest goat cross. The middle goat sees that the youngest one has crossed and reaches the conclusion that the bridge must be safe after all, but is also stopped by the troll and given the same threat. The second billy goat is allowed to cross as well after he tells the troll to wait for the biggest billy goat because he will have the most meat. The third billy goat then gets on the bridge, and is stopped by the hungry troll. When the troll gets up on the bridge however, the third billy goat is so big, that he easily throws the troll into the stream with his horns and crosses the bridge. From then on the bridge is safe, and all three goats are able to go to the rich fields around the summer farm in the hills. They all live happily ever after. The troll however was never seen again.