Mary-Claire Carter is a fictional character from the BBC medical drama Holby City, played by actress Niamh McGrady. She first appeared in the eleventh series episode "Spin", broadcast on 22 September 2009. The character was introduced by Tony McHale. Between her arrival and January 2013, Mary Claire appeared on a recurring basis, sometimes with months between appearances, as an agency nurse on Keller and AAU wards. McGrady was promoted to a regular cast member in early 2013 by newly appointed executive producer, Oliver Kent - alongside the introductions of three characters. Her first appearance, as a regular cast member, aired on 23 April when Mary-Claire received a staff nurse job on the AAU ward. She is characterised as a blunt and easily distracted character, yet a brilliant nurse. Her strong point is not diplomacy, but scratch beneath the surface and you'll find a heart of gold. McGrady has described her as "cheeky, flirtatious, and trouble."

Holby City is a British medical drama television series that premiered on 12 January 1999 on BBC One. The series was created by Tony McHale and Mal Young as a spin-off from the established BBC medical drama Casualty. It is set in the same hospital as Casualty, Holby General, in the fictional city of Holby, and features occasional crossovers of characters and plots with both Casualty and the show's 2007 police procedural spin-off HolbyBlue.