Complex sentence: She has appeared in many popular American films, but she is best known for her work in television, including roles in the television series "Twin Peaks", "Seinfeld" and "Big Love".
Split into simpler sentences: She has appeared in many popular American films, but she is best known for her work in television. She is perhaps best known for her roles in the television series "Twin Peaks", "Seinfeld" and "Big Love".