Born in the year 1968 on 22nd January in Fleet situated in Hampshire, in the United Kingdom, Raquel Cassidy’s birth name is Raquel Josephine Dominic Cassidy. She spent the better half of her early days in Fleet and she had two older brothers. Not much detail is available about how her childhood days were spent and her parent's name is not disclosed. She was enrolled as a student in the Farnborough Hill Covent situated in Hampshire in the United Kingdom.

She then decided to complete her education from the Girton College which is a college which comes under the University of Cambridge situated in Huntingdon Road in Cambridge in England. During her college days, her major was modern languages and after that, she was also a student of biological anthropology. She then decided to get a Doctor of Philosophy degree in biological anthropology. She dropped her idea of getting a Ph.D. and decide to begin her acting career. It is not known how she got interested in acting and what inspired her to become and actress, but she decided to be an actress at a very young age.

She started her career in acting in 1998 when she got the opportunity to play the character of WPC Pamela Boxer in the television show Killer Net. The turning point in her career came when she was chosen to portray the role of Susan Gately in the television show Teachers in 2001. This show helped her to garner a lot of attention and increase her fan-following. She also gained a lot of popularity for her roles in the television show Lead Balloon where she played the role of Mel Davies in 2006 and Downton Abbey where she was seen as Phyllis Baxter in 2013.

She has been a part of a large number of television shows such as The Bill as Lola Chaves in 1999, Red Cap as Staff Sgt. Neve Kirland in 2003, The Worst Week of My Life as Cassie Turner in 2004, According to Bex as Chris in 2005, Party Animals as Jo Porter in 2007, Moving Wallpaper as Nancy Weeks in 2008, Doctor Who as Miranda Cleaves in 2011, Midsomer Murders as Diana DeQyetteville in 2012, Jonathan Creek as Sharon in 2014, Vera as Gloria Edwards in 2015 and The Worst Witch as Miss Hardbroom in 2017.

She made her debut in films in 2002 when she got the opportunity to portray the character of Romy in the movie Do I Love You. She has also done some movies such as Before You Go as Felicia in 2002, Festival as Petra Loewenberg in 2005, The Boat People as Alice in 2007, Tick Tock Lullaby as Maya in 2007 and Nightwalking as Martha in 2008. Talking about the personal aspect of her life, she is not known to be married or having a husband. There is no news about any children and about her having any partner. She is a very popular actress and her biography is available on several sites. Her net worth and salary are also very high.