Father Dougal McGuire Linehan and Mathews to discard the mockumentary format and expand the Father Ted episode to a traditional sitcom, Father Dougal became one of the main characters. When writing Dougal, Linehan and Mathews drew on Stan Laurel, incorporating some of Linehan's own behaviour during moments of confusion. Linehan and Mathews saw O'Hanlon in a modernised Shakespeare play broadcast by RTÉ, and were impressed by the "weird, gormless" face he could pull. Linehan later said, "That was Dougal right there. He was just spot-on and he became our secret weapon. The show took off so quickly because Ardal was so instantly funny."
Father Ted Crilly more conservative, traditional priest. Morgan lobbied hard for the role, eventually persuading Linehan. The writers considered O'Donoghue a back-up to use should Morgan become unavailable, and later created Father Dick Byrne, Ted's recurring rival, specifically for O'Donoghue to play. Aspects such as Ted's obsession with money and fantasy of going to Las Vegas emerged while writing for Morgan, and the writers began to feel for Ted in a way they did not for the other characters. After the second series aired, Linehan said he still believed that Mathews could easily have played Ted in the show. There have been several