Mary Megan "Mare" Winningham (; born May 16, 1959) is an American actress and singer-songwriter. An eight-time Emmy Award nominee, she won Outstanding Supporting Actress in a Miniseries or Movie for Amber Waves in 1980 and George Wallace in 1998. She was also nominated for the Academy Award for Best Supporting Actress for the 1995 film Georgia.

Winningham's other film and TV roles include St. Elmo's Fire (1985), Miracle Mile (1988), Turner & Hooch (1989), The War (1994), Dandelion (2004), Swing Vote (2008), Brothers (2009), Mildred Pierce (2011), Hatfields & McCoys (2012) and four seasons of American Horror Story: Coven (2013), Freak Show (2014), Hotel (2015-16) and Cult (2017). She made her New York stage debut in the 2007 Off-Broadway musical 10 Million Miles, for which she received a Drama Desk Award nomination. and her Broadway debut in the 2013 revival of Picnic. In 2014, she was nominated for the Tony Award for Best Featured Actress in a Play for the original Broadway production of Casa Valentina.