I have an idea for 3 new mobs, White Stallion, White Pegasus, Black Pegasus. To tame these mobs, you need to craft a horse saddle. To craft a horse saddle, put three leather over the top of the crafting table, then leather all through the middle of the crafting table from top to bottom. Then put iron ingots in the remaining spots. Then you walk up to the animals, but they will run away from you, so get a regular apple (Golden apples don't work) and press Q and throw it at the animal, the animal will eat it. Then it won't run away from you anymore. Then right click the animal with the horse saddle and it will attach to it. Then right click the animal to start riding (WASD keys are used to navigate. For pegasi, SPACE is up and shift to go down).
Don't forget to add
no idea why it's not in my reactions folder but...
He's Right, you know.
Mo Creatures planned to add horses in its initial release. you can't really get out-of-date with horses.