Which Molly Shannon character was a Catholic schoolgirl on SNL?

The Molly Shannon character who was a Catholic schoolgirl on SNL was Mary Katherine Gallagher.

Mary Katherine Gallagher is a sardonic, awkward teenage Catholic schoolgirl portrayed by Molly Shannon. The character is intensely ambitious, socially uncomfortable, and prone to dramatic mood swings. Her signature behavior includes striking a heroic pose while shouting that she is “superstar,” a bit that became one of Shannon’s most recognizable SNL trademarks.

Shannon developed an early version of Mary Katherine while studying at New York University, in a comedy show directed by Madeleine Olnek. A prototype appeared in a 1995 SNL sketch, and the established character became a breakout role after Shannon joined the cast in the mid-1990s. She played Gallagher from 1995 to 2001 and returned for later appearances.

The character also moved beyond television: Shannon reprised Gallagher in the 1999 feature film Superstar. That film follows the schoolgirl’s dream of becoming a musical performer. A common mix-up is with Debbie Downer, another prominent female SNL character, but Debbie Downer was created and played by Rachel Dratch and is defined by pessimistic interruptions rather than Catholic-schoolgirl theatrics.