Most of the early cast, both human and muppet, on Sesame Street had only one name, either first or last. Gordon, Susan, Bob, Mr. Hooper, Ernie, Bert, Prof. Hastings, David, Maria, Luis. One notable exception was Roosevelt Franklin. Then we got some other characters with two names like Herbert Birdsfoot and Harvey Kneeslapper. Finally, they started giving the human cast two names such as Gordon and Susan Robinson, Luis and Maria Rodriguez, and Harold Hooper. Maybe someday, Ernie and Bert will get official last names too.