Some scripts simply call for an assortment of AMs and the end product just happened to use the Elmo puppet; other scripts specifically call for "AM Elmo", but as the AM designation dictates, the puppet is used in a more ancillary manner in these cases and shouldn't necessarily be considered authentic Elmo appearances.
AM proto-Elmo performers
The character definitively appeared named as Elmo in street scenes during Season 11 where he spoke only in mumbles. Brian Muehl originated the character, playing him in at least nine episodes until Season 15's last episode. Richard Hunt picked up the character for a brief stint of six episodes in Season 16, two of which were taped before Kevin Clash took on the character, but aired after. Clash's performance of Elmo at first emulated Muehl and Hunt's characteristics, but he soon developed his own take which became the best known version.
Five of Hunt's six performances as Elmo were shot over the course of three weeks in 1984. The sixth (Episode 2037) was shot on the morning of November 26, the same day Kevin Clash took over the character. In My Life as a Furry Red Monster, Clash recalls that Hunt literally tossed him the Elmo puppet (which he caught in mid-air) saying, "Give it a voice, Clash." Clash's first taped episode in the role, Episode 2026, was shot that afternoon.
- Season 16 (1984-1985)
Clash became Elmo's regular performer after this point, taking some time to settle in to the role. His interpretation took on elements from both Muehl and Hunt's versions of the character, including repeated phrases like "yes, yes" or "play, play" as well as shifting the softness of the voice. According to a video interview in the "Behind the Street" featurette on disc one of 40 Years of Sunny Days, Clash doesn't consider his having "found Elmo's voice" yet until Episode 2215 despite having appeared in at least twenty-seven episodes earlier that season (2096, 2097, 2123, 2131, 2135, 2146, 2149, 2153, 2155, 2156, 2165, 2167, 2169, 2170, 2173, 2174, 2176, 2183, 2186, 2187, 2189, 2190, 2191, 2197, 2199, 2204, and 2210, as well as a News Flash and a lecture segment with Kermit the Frog).
- Despite his claims to the contrary, Caroll Spinney never performed Elmo.