Gagarin is a hero, no doubt, but I would like to add that the first space traveler was a dog named Laika. There is a memorial Web Page for her.
She was one of mans best friends sent to view the heavens to make our way safe. She returned to earth a shooting star.
Buck.
Laika is actually a pretty sad story. They put poison in her food so that she'd be dead before her air got bad or reentry. I'm not an anti-animal testing nut, but you'd think they just might consider a safe reentry experiment at the time they're sending up a live creature -- get a little more scientific value out of it and have the possibility of a live animal at the end. They can use instruments to see if the cabin maintains pressure, etc., why use a live animal?
The Onion had a great take on this in "Our Dumb Century" in a story along the lines of "U.S races to kill more animals in space than Russians. They're ahead of us, but we're catching up."