Sarah Michelle Prinze (née Gellar; born April 14, 1977) is an American actress, producer, and entrepreneur. After being spotted by an agent at the age of four in New York City, she made her acting debut in the made-for-TV movie An Invasion of Privacy (1983).

Gellar received widespread recognition for her portrayal of Buffy Summers on the WB series Buffy the Vampire Slayer (1997–2003), which earned her five Teen Choice Awards, a Saturn Award and a Golden Globe Award nomination. The character was widely popular during the airing of the show and became recognized as one of the 100 greatest female characters in U.S. television. Gellar also gained significant attention for her appearances in the slasher movies I Know What You Did Last Summer and Scream 2 (1997), and for her portrayal of Kathryn Merteuil in Cruel Intentions (1999). She appeared as Daphne Blake in Scooby-Doo (2002), her biggest live action commercial success.

In 2004, Gellar starred in the sequel Scooby-Doo 2: Monsters Unleashed and the horror remake The Grudge, both of which grossed more than US$180 million worldwide. She subsequently appeared in smaller scale movies such as The Return (2006) and Southland Tales (2007), and provided her voice for TMNT (2007). Her later film credits include The Air I Breathe (2008), Possession (2009) and Veronika Decides to Die (2009). She headlined the short lived television series Ringer (2011–2012) and The Crazy Ones (2013–2014), which co-starred Robin Williams. In 2015, she joined the cast of the animated series Star Wars Rebels for season two.

Gellar met her future husband Freddie Prinze, Jr., while they were filming the 1997 teen horror film I Know What You Did Last Summer, but the two did not begin dating until 2000. They were engaged in April 2001 and married in Mexico on September 1, 2002, in a ceremony officiated by Adam Shankman, a director and choreographer with whom Gellar had worked on Buffy the Vampire Slayer. Prinze and Gellar have worked together several times; they played each other's respective love interests as Fred and Daphne in the 2002 film Scooby-Doo and its sequel, Scooby-Doo 2: Monsters Unleashed, and both provided their voices for the animated feature Happily N'Ever After (2007) and the animated series Star Wars Rebels. In 2007, in honor of their fifth year of marriage, Gellar legally changed her name to Sarah Michelle Prinze.

Together, Gellar and Prinze have two children, a daughter and a son. The family lives in Los Angeles.

In October 2015, Gellar co-founded Foodstirs, a food crafting brand and e-commerce startup selling baking kits for children.