Rupert Grint as Ron Weasley (appeared in all 8 films). Born 24 August 1988 (age 24) Grint was cast as Ron Weasley at the age of 11, having previously acted only in school plays and at his local theatre group.From 2001 to 2011, he starred in all eight Harry Potter films alongside Daniel Radcliffe and Emma Watson.Grint chose to try out for the part of protagonist Ron Weasley, one of Harry Potter's best friends at Hogwarts, because he had ginger-coloured hair, and was a fan of the book series.upert Grint as Ron Weasley (appeared in all 8 films). Born 24 August 1988 (age 24) Grint was cast as Ron Weasley at the age of 11, having previously acted only in school plays and at his local theatre group.