The source provides a detailed and personal ranking of the 15 greatest screen performances by legendary actor Jack Nicholson. It introduces Nicholson as a "force of nature" who defined American cinema for decades, capable of portraying a vast range of roles from psychopaths to romantics, often within the same character. The list critiques specific performances, offering commentary on his work in films such as The Departed, One Flew Over the Cuckoo's Nest, and Chinatown, highlighting Nicholson’s ability to embody "madness itself." The text concludes by noting that Nicholson has retired but left behind an unmatched cinematic legacy as the "grinning, dangerous American original."