Hmm, because this will never happen, i'm going to say it anyway
Giant leaping sharks found in deep water, tons of heath, you most likely need a boat mounted machine gun to keep it from landing on you and destroying your boat (with you in it).
Giant swooping birds (griffins anyone?) that attack you and take blocks off your house (light ones like wood, not stone). Even pick you up and carry you through the air, dropping you at some point (lets hope you have great aiming skills with that boat mounted machine gun).
Finally as a boss for the nether, a double sized zombiepigman with a diamond sword riding a ghast (also double sized). The ghast is three times the speed of a normal ghast, and it shoots out lava blocks that land and start flowing, twice the distance of normal placed lava in the nether. It also BURNS THOUGH COBBLESTONE!
Yeah, i could come up with hundreds more.
Just think huge and awesome looking.
The Meaning of Life, the Universe, and Everything.
I want a knight. He has a unique set of armor, being black-colored iron armor with a full face mask, and an iron sword. He has full access to the abilities to jump, block, and take advantage of critical hits. If you kill him, he has a chance to drop his sword and one piece of his armor, along with some potentially high-level materials. They have a very low chance of spawning, only spawning in small above-ground dungeon typ structures and Strongholds. They only respawn in the above-ground buildings, due to the importance of said Strongholds.
Oh, I just thought of another. Turret walkers. They're 2 blocks by 3 block by 2 blocksand have a detection radius of 16 blocks. They walk on 4 mechanic legs When you enter it's detection radius, it turns toward you, clamps itself to the ground and aims a rapid fire crossbow at you. You then have 10 seconds to destroy it with a 4 swipes to the gun or an arrow shot to the chestplate.
They should add monkeys that we can tame and have do small tasks for us, like throw their poop at creepers, retrieve fruit from trees for you (once apples are added), and have them ride your pet wolves like a horse.
Polar bears would be cool. Passive unless attacked like wolves, of course.
Aliens would be cool too. Maybe have a randomly generated UFO crash spawn in worlds like villages do. and have the Aliens be passive unless attacked and maybe some rare exclusive xbox only goodies that can be taken from the UFO and the Aliens.
I like the horse idea. It would put the saddles to good use for sure. And there should be different varieties of them. So you can breed them and maybe dye them. And fish that you can see swimming in the water. Sharks would be awesome too. And some underground mobs that only spawn underground. Instead of creepers, zombies, etc. Maybe some bats, big worms. Birds in the sky would be sweet! If you catch em you could make a bird cage and breed them. Minecraft needs more animals added to it. I think it would be cool to have a massive farm with different animals. Maybe like deer, donkies, monkeys, llama, or goats.
If I could add any mob, it would be a massive tunneling worm. It would be 10 blocks long, 1 block wide and could tunnel around, break certain blocks at will, and spawn in massive underground nests, possibly containing a worm queen that hatches the other worms.
sounds similar to an enemy in teraria (misspellings FTW)
I WOULD ADD PIRANAHS AND gigantic four legged things like a t-Rex but you had to avoid it or else if it sees you it would be hard to get away from I would recommend hiding right behind a tree and prey that te t rex won't step on you
And the piranhas should come up and take 1 or 1and a half hearts away from you