People in the wizarding world love their pets. Even Lord Voldemort (who hates everyone) has his beloved giant killer snake, Nagini.
Lord V used to be Tom Marvolo Riddle, and was a terrible cheater at anagrams. I wonder if some people ALMOST figured out that Tom Riddle was really Voldemort when they noticed that all the letters required to spell out "Voldemort" were in his name. I'm sure anyone would've given up, though, when they noticed a couple of extra letters left over. Adding "I AM" before "LORD VOLDEMORT" is anagram cheating, Tom! Your new name should've been "Lord VOLDEMORTIAM" or something.
But then, he IS evil, so I suppose we should've expected cheating, but even on something as sacred as anagram clues? Even the Riddler would never do that.
A confession: Lord Voldemort has never completely done it for me as a villain. I love a good bad guy, but for some reason old moldy Voldy has never seemed as scary as I think he's intended to be. Maybe it's because when we first learn of him he's already been defeated by a baby. Maybe it's how weak he seems when he's hiding out on the back of a milquetoast's head or being carried around in fetal form (wouldn't it have been hilarious if he'd made Peter Pettigrew or somebody carry him around in one of those baby packs like Zach Galifanakas wore in The Hangover?). We get such a strong impression of him as something weak early on that even when he regains strengh, it's hard to shake that feealing of weakness.
Or maybe it's the lack of a nose. How can he smell your fear without a nose?