Ghoul Rat

These guys are found everywhere that's spooky like in Arbiter's Grounds and Hyrule Castle in Twilight Princess. They are invisible and they use that advantage to cling on to you and slow you down, but to the sharply "sensed" animal, these rats are easy pickin'. When the rats are on you, turn into your wolf form and activate your senses then do a spin attack to wipe them out. When in wolf form, you'll know their clinging to you, by seeing Midna panicking. They don't inflict damage, so don't bother killing them right there and then unless you want to move faster.