A wether is a male sheep that has been castrated. Wethers don't behave agressively in the fall. They put their feed towards growing wool and generally are easy keepers. If you want a sheep to harvest fleece from for your spinning projects and/or a friendly animal that eats your weeds and grass, consider keeping a wether.
We find that the icelandic leadersheep make great wethers. We have heard that in Iceland, they traditionally wethered their best leadersheep rams, so they could keep them with the ewe flock to lead the flock in when bad weather threatened. Leadersheep make interesting additions to a hobby farm, as they are very affectionate and curious.
As with all livestock and pets, pet wethers must be housed properly and respected for their ability to cause damage if handled improperly. The way they naturally play and interact with each other can be very painful to people if their normal behaviour is not respected and understood.