Complex sentence: Robert Donley (1911-2004) was an American actor most noted for playing "Rocky" Rockford in the pilot for "The Rockford Files" before being replaced by Noah Beery, Jr. for the series itself.
Split into simpler sentences: Robert Donley (1911-2004) was an American actor. Donley remains most noted for playing "Rocky" Rockford in the pilot for "The Rockford Files" before being replaced by Noah Beery, Jr. for the series itself.