Kate Gordon Siegelbaum (born August 9, 1982) is an American actress and screenwriter. She played Theodora Crain on The Haunting of Hill House and Viola Lloyd on its follow up The Haunting Of Bly Manor.
She was born in Silver Spring, Maryland. She attended St. Andrew's Episcopal School in Maryland, and graduated from Syracuse University in 2004. She is Jewish.
She made her acting debut in the film The Curse of The Black Dahlia, which was released on January 23, 2007. That same year she went on to star in Hacia La Oscuridad which had its world premiere at the Tribeca Film Festival on April 28, 2007. She also appeared in Steam alongside Ruby Dee and Chelsea Handler. In 2008, Siegel appeared in the short film Knocked Down which was directed by Ted Collins. In 2009, she made her television debut in Ghost Whisperer as Cheryl. In 2010, she appeared in Numb3rs as Rachel Hollander. She then appeared in an episode of Castle. That same year she appeared in the drama-thriller Wedding Day.
In 2013, she appeared in Man Camp. That same year she appeared in Oculus, a horror film written and directed by Mike Flanagan. The film had its world premiere at the Toronto International Film Festival in September 2013, and was released in April 2014. She also appeared in an episode of Mob City. In 2014, she appeared in Demon Legacy.
In November 2015, it was revealed that she and Mike Flanagan would be adapting the young adult novel 13 Days to Midnight into a film.
In 2016, she made her screenwriting debut opposite her husband Mike Flanagan in Hush, the film had its world premiere at South by Southwest on March 11, 2016, and was released on Netflix on April 8, 2016. In July 2016, she starred in a commercial for Stelara psoriasis medication. That same year, she appeared in Ouija: Origin of Evil, also directed by Flanagan, which was released on October 21, 2016.
In 2017, she starred alongside Carla Gugino and Bruce Greenwood in the film adaptation of Stephen King's Gerald's Game, which was also directed by Flanagan. The film was released on September 29, 2017, by Netflix.
In 2018, she had a starring role as Theodora Crain in the Netflix supernatural horror series The Haunting of Hill House, based on Shirley Jackson's 1959 novel of the same name. She also narrated the podcast Calling Darkness and has been a voice actor for The NoSleep Podcast.
In a 2008 interview, she stated that she identifies as bisexual. She married director Mike Flanagan in early 2016. They have two children; a son, Cody Paul, and a daughter, Theodora Isabelle Irene. She is also a stepmother to Flanagan's first son, Rigby.