He is voiced by series co-creator Trey Parker and debuted in the season one episode "Mr. Hankey, the Christmas Poo".

[1] The school counselor at South Park Elementary, he is best known for saying "m'kay" at the end (or beginning) of most of his sentences.

This is also supported by the episode "Taming Strange", in which popular 1980s music plays from Mackey's computer on the school intercom while trying to use the new Intellilink system, such as Lionel Richie's "All Night Long (All Night)" and Glenn Frey's "The Heat Is On" from the Beverly Hills Cop soundtrack.

[3] Mackey holds generally left-wing political views, as he protested against the Iraq War in the season seven episode "I'm A Little Bit Country".

Later in the episode, he threatened to rape Stan Marsh in the mouth if the latter threw any of the clutter in Mackey's office away.