What is Mr. Snuffleupagus's first name?

Mr. Snuffleupagus's first name is Aloysius.

The character is formally named Aloysius Snuffleupagus, although viewers almost always hear him called Mr. Snuffleupagus, Snuffleupagus, or Snuffy. His first name is especially associated with references to his family: his mother uses “Aloysius,” while the shorter nicknames are used by Big Bird and the other residents of Sesame Street.

Snuffleupagus first appeared in 1971 as Big Bird's large, shaggy best friend. For many years, Big Bird was the only character who could see him clearly. Snuffy would disappear before the adults arrived, leading them to assume that Big Bird had an imaginary friend.

That storyline eventually changed in 1985, when the adults finally met Snuffy. Sesame Workshop retired the premise partly because producers worried it might discourage children from telling trusted adults about serious problems. His name is also often misspelled or hyphenated as “Snuffle-upagus,” but “Snuffleupagus” is the standard spelling.