Kate Walsh, born Kathleen Erin Walsh on October 13, 1967, in San Jose, California, is an American actress and businesswoman. She grew up in a Catholic household in Tucson, Arizona, and graduated from Catalina Magnet High School before studying acting at the University of Arizona.

Kate Walsh moved to New York City and joined a comedy troupe, Burn Manhattan, supporting herself by waitressing. She later moved to Chicago and worked with the Piven Theatre Workshop.

Her television career took off in 1997 when she appeared on "The Drew Carey Show" as Drew Carey's love interest, Nicki Fifer.

She went on to star in the ABC medical drama series "Grey's Anatomy" as Dr. Addison Montgomery from 2005 to 2012, and in the spin-off series "Private Practice" from 2007 to 2013. Her other television roles include Rebecca Wright in "Bad Judge," Olivia Baker in "13 Reasons Why," and The Handler in "The Umbrella Academy."

Kate Walsh is a successful entrepreneur. In 2010, she founded Boyfriend LLC, a beauty and lifestyle company. She is also a social activist, having been elected to the board of the Screen Actors' Guild and campaigning for various social causes, including Planned Parenthood, pet adoption, and sea turtle protection.

Kate Walsh has also campaigned for U.S. presidential candidates Barack Obama and Hillary Clinton.