Fox's television roles include the BBC drama Pride and Prejudice (1995), the PBS British/German television serial Rebecca (1997), ITV Granada's Henry VIII (2003), BBC's Gunpowder, Treason & Plot (2004), the 2005 BBC miniseries The Virgin Queen (2005) and the ITV crime drama series Fallen Angel (2007). She also appeared as Morgause in the BBC's Merlin, beginning in the programme's second series. Fox also starred in Delicious (2016). She stars as Dr. Nikki Alexander on BBC crime drama Silent Witness, having joined the cast in 2004 following the departure of Amanda Burton. Fox is the longest serving cast member since the departures of Tom Ward in 2012 and William Gaminara in 2013. Fox has currently played the role of Nikki for 16 years.