Why Every Lead Actor Left Doctor Who
9. Peter Davison
As previously mentioned, Peter Davison wanted to stick to a three-year stint after listening to Patrick Troughton's advice about not being typecast. So that's exactly what he did!
However, there may be a little bit more to the story than that.
Though Davison was happy with his final season in 1984, he found the middle part of his run rather frustrating, clashing with Nathan-Turner over various creative decisions. Davison wished to bring more levity to his Doctor, which his superior consistently shot down.
Davison had also noted how long Tom Baker stayed in the role, and was concerned that staying any longer than three years might affect his future job opportunities.
And so, the Fifth Doctor regenerated on 16 March 1984, almost three years to the day since his first appearance at the end of Logopolis.