Professor Margaret Walsh, known as Professor Walsh or, more informally, Maggie Walsh, is a fictional character in the U.S. television series Buffy the Vampire Slayer. The character is played by Lindsay Crouse.
Maggie Walsh was introduced to the series in season four of Buffy, initially as an ally of the Slayer, becoming an enemy when she plotted to kill Buffy Summers to remove her as a threat.
Maggie Walsh first became involved with Buffy when she was enrolled in the professor's Psychology class along with Willow and Oz in their first term at UC Sunnydale. At the university, Maggie has a fearsome reputation as an academic and hardworker. However, like Buffy, Maggie also had a secret double life as a chief member of The Initiative, a secret government agency located below the university. The Initiative employed a team of commandos, led by Riley Finn tasked with capturing demons and vampires. The captured demons would be taken back to the Initiative where experiments would be carried out with them. Maggie was also involved in Project 314, a secret part of the Inititaive which was creating a hybrid demon-humanoid-mechanoid known as Adam. Demons captured by the Initative would be dissected to provide parts for Adam.
Maggie maintained a close relationship with Riley Finn, who looked upon her as a mother figure. As Riley developed a relationship with Buffy, the identity of the slayer became known to Maggie. Initially thinking Buffy as a useful ally, Maggie soon took a dislike to her constant questions and unpredictable nature, especially over Project 314. Maggie was also jealous of Buffy's hold over Riley, and spied on them making love on the Initiative's monitors.
Eventually Maggie decided to kill Buffy by setting her on a mission where she would be ambushed by two demons released from the Initative's holding cells. However Buffy defeated the demons and appeared on the monitors when Maggie prematurely announced Buffy's death to Riley. An embittered Maggie now retreated to the labs of Project 314 where she plotted how to use Adam to defeat Buffy. However Adam awoke and impaled Maggie, killing her, and escaped from the Initiative.
Maggie appears in the penultimate episode of season four, "Primeval", as a walking corpse, employed by Adam to finish off Project 314, the creation of more like him, manufactured from the parts of demons and humans combined. It was also revealed that Maggie had set Riley up to be part of 314, by planting a chip within his body that could be used to control his body. Maggie's corpse attacked Buffy when she tried to rescue Riley but was destroyed.