Lucia Ella Keskin (born 9 February 2001), also known as Chi with a C, is an English comedian, actress, writer, YouTuber and internet personality. She began her career posting skits and videos on YouTube, before making appearances in comedy series including Big Boys and Sneakerhead. In 2024, she wrote and starred in her own BBC sitcom Things You Should Have Done.

Keskin is from Margate. She attended Dane Court Grammar School, Broadstairs. She briefly worked as an assistant in a dance school, after leaving education with just one GCSE. She also trained at The Canterbury Academy institute of Performing Arts studying musical theatre.

In January 2022, Keskin announced she was in a relationship with a woman. However, she confirmed she was again single a year later via an Instagram post

Keskin began uploading videos on YouTube in 2017. Her first viral video was an impersonation of Gemma Collins uploaded to Facebook in 2018 and first YouTube hit was a September 2018 reenactment of Friends' pilot episode. Subsequently, Keskin appeared on BBC News, accidentally Skypeing the channel during another interview. She has performed several other parodies of TV shows and characters, using greenscreen. In The Daily Telegraph, Eleanor Halls described Keskin as "the funniest person online right now." Keskin featured at the 2019 Summer in the City festival.

In 2020, Keskin's parody of American Horror Story was praised by Sarah Paulson, an actress of the series. Paulson agreed with comments that encouraged Netflix to commission Keskin for her own show. In December 2020, Keskin appeared in a YouTube video advertising Sky Q alongside breakfast television presenter Lorraine Kelly, whom Keskin has impersonated in the past. They discussed popular television programmes available on the service, in addition to Kelly ranking several of Keskin's parody videos including a breakfast television parody in which she parodied Lorraine.

In May 2022, Keskin made her television acting debut in the Channel 4 series Big Boys as Kelly. In July 2022, Keskin starred in the sitcom Sneakerhead which aired on Dave. In May 2023, Keskin announced that she had written and would be starring in a six-part sitcom for BBC Three titled Things You Should Have Done. It is based on a dysfunctional family concept in where the daughter Chi played by Keskin, learns to cope with independence following the death of her parents. It fully debuted on BBC iPlayer in February 2024, and released episodes live weekly on BBC Three. In March 2024, she appeared in the first episode of the third series of Mandy as Shona, a plane passenger who couldn't get the film Jumanji to play on her in-flight entertainment system.