The unusual Morph mod allows you to turn into any mob from Minecraft. In a regular game, it can be used only for entertainment, but it can be very useful if you create a plot-based map or RPG elements.
To turn into any creature from the game you only need to install this mod and press the X button after starting the game. A special menu will open in which you can select the desired mob. Creatures added using any other mods will also be displayed in the menu, and you can turn into them.