Pink Floyd’s Dark Side of the Moon was definitely uncharacteristic compared to their previously released material, and it catapulted them into the top tier of successful musicians of their generation.
The Beach Boys dramatic change from surfer music and warmed-over Chuck Berry rewrites to to the complex orchestration of Brian Wilson’s best work.
The Bee Gees changing from semi-successful British folk-rock to the most successful disco group.
The Eagles transition from country-rock to California rock.
Linda Rondstadt and her shift from California pop to big band standards.