MacKenzie "Big Mac" Chalker, better known to his friends and colleagues simply as Mac, is a former health care assistant who worked at Holby General Hospital's Emergency Department from 2007 until 2016.

Interference on the Wards (2012)

Big Mac came up in the lift from Holby Emergency Department, where he brought up a patient who had breathing difficulties to Luc Hemingway in AAU. He was later seen helping Elliot Hope find files about a security guard at the hospital, as there was no next or king in the patient's file. Big Mac and Elliot sat down in a room going through all these old folders which contained staff's personal information for when they joined the hospital, they finally found the patients notes which contained the security guards next of king to be contacted.