|Portrayed by||Jamie Thomas King|
|First appearance||Guy Walks Into an Advertising Agency|
|Final appearance||Guy Walks Into an Advertising Agency|
|Employer||Puttnam, Powell, and Lowe|
Guy MacKendrick was an accounts executive of London-based advertising firm Puttnam, Powell, and Lowe.
MacKendrick was brought in by PP&L to take over the Sterling Cooper Advertising Agency as Chief Operating Officer to replace Lane Pryce who held a similar role after PP&L's purchase of Sterling Cooper. Saint John Powell and Harold Ford expressed much enthusiasm for him, crediting his "inestimable charm" and having degrees from both Cambridge University and the London School of Economics. During an introductory meeting with the partners of Sterling Cooper, Powell also mentions that MacKendrick had previously worked in finance for three years and at McCann Erickson for two years likely as an accounts executive, acquiring the Mercedes-Benz advertising account. Accounting for his education and relatively short five-year post-graduate career experience, it can be estimated that MacKendrick was in his mid to late 20s in 1963.
During the drunken office party to welcome the company's reorganization, Lois Sadler accidentally runs over MacKendrick's foot with a John Deere riding lawnmower. Joan Holloway saves his life by quickly placing a tourniquet on his leg, however, his foot is ultimately amputated.
Because of this disfigurement Powell and Ford decide that MacKendrick has no future with the firm and is fired with Pryce remaining at his post indefinately. ("Guy Walks Into an Advertising Agency")