Patrick began his acting career with Toronto's famous Second City Theatre Company. Then he took to the road as a Stand Up comedian headlining in Universities and clubs throughout North America with highlights including being the opening act for Dionne Warwick and Smokey Robinson.

Eventually, episodic television beckoned. First with the hilarious Red Green Show with fifteen seasons as the loveable, nerdy, techno-geek, Harold; while simultaneously performing five seasons in the acclaimed dramatic series TRADERS. Variety newspaper noted, Mr. McKenna 'has made television history' by being awarded Gemini's for both the 'Best performance by a Lead Actor in a Comedic Series' and 'Best performance by a Lead Actor in a Dramatic Series' in the same year on the same night.

Currently Patrick can be seen in TVO's ongoing hit medical series, HARD ROCK MEDICAL and the season favourite, WILL YOU MERRY ME? on WTN. With any remaining free time, Patrick lends his voice to no less than five regular animated series. 

Next you can see Patrick returning to MURDOCH MYSTERIES as the bumbling Inspector Slorack and then as a fast-talking con artist in CBC's new hit, ​FRANKIE DRAKE.