The San Gabriel Mission Playhouse is rumored to be haunted by the ghost of its most famous patron, John S. McGroarty, who wrote the epic The Mission Play that was staged there for over 3,000 performances. While there are no specific details of how he haunts the location, the belief is that he remains connected to the theater. Additionally, legends persist of hidden tunnels beneath the stage, where it's said bodies were hidden during the Great Depression. The Spirit of John S. McGroarty: John S. McGroarty was the author of The Mission Play, a historical epic about the founding of California's missions. The play was performed at the San Gabriel Mission Playhouse for 3,198 shows. The rumor is that McGroarty's spirit still lingers in the theater. There are supposedly hidden tunnels located beneath the stage of the playhouse. It is rumored that these tunnels served as a hiding place for bodies during the Great Depression.