What is the first name of Buffy's mother?

The first name of Buffy’s mother is Joyce; she is Joyce Summers.

Joyce is Buffy Summers’s mother in Buffy the Vampire Slayer, played by Kristine Sutherland. She begins the series as a divorced parent who moves with Buffy to Sunnydale and runs an art gallery. At first, Joyce does not understand that Buffy is the Slayer or that her daughter spends her nights fighting vampires and demons.

That changes near the end of season 2, when Buffy is forced to reveal the truth. Although Joyce initially reacts with shock and anger, she gradually becomes a supportive presence in Buffy’s life. Her ordinary parental concerns—school, dating, safety, and responsibility—provide a grounded counterpoint to the supernatural dangers surrounding the family.

Joyce’s storyline becomes especially important in season 5. She develops a brain tumor and dies unexpectedly in the episode “The Body,” a major turning point for Buffy and the series. Viewers sometimes confuse Joyce with Dawn, Buffy’s younger sister, or with Buffy’s father Hank Summers, but Joyce is specifically Buffy’s mother and her first name is Joyce.