A series of animated inserts produced for Sesame Street featuring an animated version of Cookie Monster (voiced by David Rudman) and an animated version of Elmo (voiced by Kevin Clash) singing about the various sounds different letters make. The segments debuted in Season 40, with some subsequent editions premiering in following seasons.
The segments were produced in 2008 for Sesame Street English. The animation was designed by Superdeux and animated by Peter Belsky. The songs were written by Cathi Rosenberg-Turow and Russell Velázquez. The segments, dubbed in Spanish, have also been featured on Plaza Sésamo, however, while the spanish counterpart does similar to what its english counterpart did; The words featured in the spanish letter song series are different compared to its english counterpart.