Yes, and they're brilliant!
My son's room has a HUGE Super Mario on the wall!
You can either get them as stickers, which you literally just peel off and stick to the walls, or decals, which are a bit trickier but have a better finish.
If you go down the sticker option, then be sure to make sure the wall is super-clean beforehand and have a sponge at the ready to get rid of any bubbles.
With the decals, you peel off a backing paper, put it where you want it (if it's large you'll need to use some masking tape to hold it there) and then use something like a credit card to rub over the design and transfer it onto the wall.
The first one I did I screwed it up completely and it had to go in the bin. Just make sure you thoroughly rub over every area, or as you pull the paper off, some it will still be stuck and will rip away from the stuff that's transferred onto the wall.
Hope that makes sense! :-)