Blue Bird was a superhero character invented by Big Bird in Season 20 on Sesame Street. The puppet was modified from the blue-colored Bird Bird outfit used in Follow That Bird, retaining only the torso (adding new arms, legs and head).
The character only appeared in two scenes on the show. In one segment, Big Bird writes a story about Blue Bird fighting a villain played by Maria (who beforehand declined spending time with Big Bird due to her work schedule). In the second and final segment, Bob wonders where missing socks go in the laundromat, prompting a story where Blue Bird fights the evil Sock Snatcher.
Performer Rick Lyon notes the concept behind the character:
“The idea was to give Big Bird a fantasy life - Blue Bird did heroic things Big Bird dreamed of, including flying. The idea was not entirely unlike the current Baby Bear fantasy character Hero Guy.”
However, the segments proved too expensive to produce on a regular basis, and the character was dropped.