Complex sentence: Comedian Jon Lovitz, who played Llewellyn Sinclair and Ms. Sinclair, made his fourth guest appearance on "The Simpsons"; he had previously voiced characters in "The Way We Was", "Brush with Greatness", and "Homer Defined".
Split into simpler sentences: Comedian Jon Lovitz, who played Llewellyn Sinclair and Ms. Sinclair, made his fourth guest appearance on "The Simpsons". He had previously voiced characters in "The Way We Was", "Brush with Greatness", and "Homer Defined".