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Ron is Kenneth Parcell's mother's boyfriend. He is played by Bryan Cranston. 

Ron (Bryan Cranston), with step-son Kenneth (Jack McBrayer)

It is implied that Kenneth had an extreme dislike for Ron, and that he was unaware that Ron and his mother Pearlene had sexual relations. Ron is portrayed as kind, but somewhat dimwitted, who can play the guitar and write his own songs. In the episode "Governer Dunston", Season 7 episode 2, it is revealed that Ron and Pearlene had been married for seven years.