The aim of the cameo appearance is usually quite simple: to increase the number of viewers. The producers of a TV show, for example, will realize that a big-name star's appearance will attract attention, will leak it ahead of time and, thus, cause more viewers to tune in to watch. Sometimes a well-known personality will want to outdo other celebrities who have made recent cameos, or promote themselves or their own shows. In fictional franchises such as comic books, the brief appearance of a real person or established fictional character can give the sense that the world of the story is not strictly limited to the scope of a fantasy world.
In the Hollywood, cameo appearances are typically utilized to get an easy laugh, as "The Independent" newspaper points out. Established actors may also appear to reinforce perceived notions about them or to play against type. An example of the latter is Tom Cruise's uncredited appearance in the movie "Tropic Thunder." Here, he portrays a physically unattractive, foul-mouthed producer in contrast to the actor's usual handsome, clean-cut characters. Sometimes personalities appear to mock their own profession or introduce a surreal element to a scene. An example of the latter is rock star Bruce Springsteen's dream-like appearance in "High Fidelity."
Cameo appearances on television are usually made for the same reasons as in the movie industry. They can also lend a particular scene a sense of realism. The British singer Adele, for instance, had a tiny part in U.S. series, "Ugly Betty." Here, her appearance as herself in a scene involving a fashion shoot wasn't out of place. Other TV shows thrive on regular cameo appearances by guests and such cameos come to be expected by viewers. Some of these shows include "The Simpsons," where cartoon versions of famous personalities, including Danny DeVito, Leonard Nimoy and George Harrison, have appeared in small parts.
Video games don't tend to be frequented by computerized versions of real-life celebrities but, instead, by fictional characters from other games who will be recognized and appreciated by players. Sometimes these appearances are just for fun, other times they add to the game's sense of realism. One example is in "Grand Theft Auto: Liberty City Stories," wherein the voices of characters from other titles in the "Grand Theft Auto" series can be heard on a car radio. Game designers might also place characters from popular titles in the game worlds of new releases in an attempt to entice players familiar with the character to try the new game.