I call the end of a loaf of bread the "heel” of the bread, but you also hear "butt of the bread" (that just sounds unappetizing) or simply the "end of the bread." Presumably they call it the heel because its hard and rough, just like the heel of a foot. I like this expression.
Apparently in Japanese, a load of bread does not have heels. It has ears! At first this sounded strange to me, but thinking about it, the ends of a loaf of bread are one on each side, just like your ears. Thus, pan no mimi パンの耳. In English the words that we use to signify those crusty slices of bread vary from person to person. I wonder if the same is true in Japanese? Maybe there's also a パンのおしり.
There's an old wives' tale that says if you eat the heel of the bread before eating the middle, you will never make ends meet in life. Imagine how many poor suckers there are in the world, whose only sin was to not like the crusts. (Does anyone remember the "Richie, eat your crusts" skit from Bill Nye?)
The real reason for eating the heel last is probably to keep the middle fresh, but whether the old wives' tale version is true or not I never eat the heel of a loaf bread without eating the slices in the middle first.
In my opinion bread ears are the tastiest part of the bread, especially if they are toasted.