Crystal Yu is a Hong Kong-British television, film and stage actress. She played Lily Chao on the British BBC medical drama Casualty from 2013 to 2017.

Yu, born in Hong Kong, came to London at the age of 11 when she was offered a place at the Elmhurst School of Dance and Performing Arts (formerly known as Elmhurst Ballet School).

As well as acting in theatre, films and TV, she gives up her spare time to work closely with The Royal Academy of Dance and The Jack Petchey Foundation, bringing dance programmes to secondary schools, Special Educational Needs schools and Pupil Referral Units. Yu is fluent in Cantonese, Mandarin and English.

In 2016, Yu was nominated for the Female Actress of the Year honour at the BEAM Awards, an organisation that celebrates minority talent, for her role as Dr. Lily Chao. After four years in Casualty, Yu left the role and her final episode was broadcast on 4 November 2017.

In 2022, she appeared in episodes of Doctor Who and Neil Gaiman's The Sandman. The following year, she appeared as Ms. Cheng in another Gaiman project, Good Omens.