Grover's Mommy plays an integral but often unrecognized role on Sesame Street. She has been seen almost exclusively in print, including the many illustrated books starring her son Grover, in many different incarnations. She was also occasionally seen in photographs, as a photo puppet, such as on the cover of Volume 4 of The Sesame Street Treasury. Over the course of time, her appearance has fluctuated greatly.
Her earliest known appearance as a Muppet is a 1974 sketch in which Grover speaks to the audience about being afraid of the dark. At the end of the sketch, his mom (Frank Oz) enters his room to kiss him good night. Another early appearance (circa 1981) involves his mother (Kathryn Mullen) coming into the bathroom while Grover is telling the audience about how to take a bath. She appears in illustrations as part of the video Five Sesame Street Stories, with an unknown voice actor.
She has recently appeared (performed by Stephanie D'Abruzzo) in a brief Elmo's World sequence (from the "Families" episode), with her son as his alter-ego Super Grover, as her own alter-ego, "Super-Mommy". Grover crashlands, screaming "Moooommy!" and his mom follows yelling "Soooonny!" crashing on top of him. They recover, acknowledge each other, and both faint. (Super Grover also refers to his mother -- "Her name is Super Mommy!" -- in a sketch with two boys fighting over an apple.)
In A Celebration of Me, Grover (performed by Eric Jacobson), Mrs. Monster attends a benefit dinner in her son's honor.
In her first appearance in puppet form, she was gray-green in color (As she was originally based from the first Grover puppet). In later appearances, she has blue fur like her son.