Snuffy is an elephant with brown fur and vocal cords (A Snuffleupagus). Best friend of Big Bird. He shakes the ground when he runs or jumps so me must be pretty darn heavy for his size.
He's 4 years old and was originally unseen by anyone except Big Bird.
My spelling of his name is verified by official Sesame Street Books and by the official Sesame Street web site! So there! :-P
Also, he's hawaiian.

Snuffy The Suffle-upagusIs a Brown Snuffle-upagus.
He lives with his mom and dad, and his sister Alice on Sesame Street.
He has a big trunk he's shaggy, and he has a deep voice.
Snuffy is a nick name his real name is Aloysius Snuffle-upagus
his best friend is Big Bird, But Snuffy just calls him Bird. At one time on the show he was just Big Bird's invisible friend.But later everyone could see him.

His real name is spelled "Aloysius." No one on Sesame Street other than Big Bird ever saw Snuffy for the longest time, and they thought he was Big Bird's imaginary friend. Adults started seeing him in 1985, according to the Children's Television Workshop web site.

He's no longer invisible. It was decided that having adults disbelieve Big Bird about what he saw sends the wrong message to children. Adults should not dismiss children's tales out of hand, and children need to learn that adults will listen to them. Which I can understand, yet it's sad that such precautions are needed.

Birthday: August 19

Favorite Songs: "He Ain't Heavy"; "Something's Coming"

Best Friend: Big Bird (he calls him "Bird")

Quote: "Oh, dear." (Try saying it slowly, holding your nose.)

Likes: Games; cabbage; spaghetti

Dislikes: When nobody believes he exists

His weepy eyelashes make Mr. Snuffleupagus look somewhat morose at times, but he's not really such an Eeyore.

Full Name: Aloysius Snuffleupagus

Originally From: Hawaii

Scientific Name: Snuffle upagus

Shoe Size: 65 GGG

Philosophy: Take it slow -- real slow

Hobbies: Roller-skating with Bird

Voice and Puppetry: Jerry Nelson, Martin Robinson