Sian Brooke is a British actress known for her roles as Laura in the series "Everything About George," Lori in "Cape Wrath," and Eurus Holmes in "Sherlock." Sian Elizabeth Phillips was born in Lichfield, Staffordshire, England, and is the youngest of three children. She took a stage name to avoid confusion with actress Sian Phillips, choosing the surname Brooke after a general from the English Civil War who served in Lichfield.

She is the daughter of a policeman and a teacher. Her parents are Welsh. Brooke received her early education at Friary School in Lichfield. At the age of 11, she first joined the Lichfield Youth Theatre, then became a member of the National Youth Theatre and subsequently trained at the Royal Academy of Dramatic Art, from which she graduated in 2002.