Most necessary cameo:
Mick Jagger on “Knights of Prosperity”
Like fancy shoes and smoothie boosts, pop star cameos are frequently superfluous to the main action. But occasionally, the storytelling fates align to place the cameo central to the entire project. Such was the case with ABC’s short-lived comedy “The Knights of Prosperity,” in which several down-and-out guys conspired to rob Mick Jagger’s swanky New York apartment. Strange premise, and not one that requires Jagger’s continual presence. But without his cameo appearance in the series’ pilot, the whole enterprise would have just felt hollow. (Dave Hogan / Getty Images)