A beetle creeps along the ground. Moving slowly and silently, it creeps up on you. When you feel the touch of tiny insect legs on your skin, you shudder, because bugs give you the creeps.
Creep has a long history and a subtle variety of meanings. In its earliest recorded usage, it described the movement of legless creatures like snakes and worms. By the sixteenth century, creep meant "move slowly" and "move with stealth" like when you creep up to your brother to startle him. Charles Dickens coined the phrase, the creeps, to suggest the shuddering sensation you get when you see something gross and scary. A creep is a person who makes your skin crawl, a meaning that has been used in American English since 1935.