Helen Virginia Horton (November 21, 1923 – September 28, 2007) was an American actress. She was born in Chicago and had a brief career in New York. She married Hamish Thomson and lived near London. She worked extensively in British television, radio and theatre, and had three children; her granddaughter is the English actress Lily James. Horton voiced the ship's computer, "Mother", in the 1979 film Alien.

Horton attended Northwestern University where she became lifelong friends with Patricia Neal (Helen Benson in The Day the Earth Stood Still). She was well thought of in the drama department and was cast as Viola, the lead role in Twelfth Night, with Neal cast as Olivia, in a university production of the Shakespeare play.

In September 1945, Horton and Neal took a shared apartment in New York and looked for work. They both got parts in a production of Seven Mirrors at the Blackfriars Theatre.

Horton took over from Vivien Leigh as Blanche in A Streetcar Named Desire after the play's London run was completed and it began to tour the United Kingdom. When Neal mentioned the connection to Leigh, she remarked "No one takes over for me, dear. When I leave a play, it's over."

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