Johnny Castaway is a screensaver released in 1993 by Sierra Entertainment, also known as Screen Antics.Johnny relaxes with a book.

The screensaver depicts a man stranded on a very small island with a single palm tree. It follows a story which is slowly revealed through time. It takes many days to catch on to the story. While Johnny eats, fishes, builds sand castles, and sleeps on a regular basis, there are a number of unusual events such as the island getting crushed by a ship that Johnny attracted, Johnny getting tied up, and a mermaid coming to the island. Some have studied the screensaver for years and still have yet to see some of the unusual scenes.

"Johnny Castaway" also features holidays of the year such as Halloween, Christmas, July 4th and others. The animations went as normal in those times, except for some detail representing the date. For example, in the last week of the year, the palm tree would have a "happy new year" banner. Halloween has a jack-o'-lantern in the sand, and so on. This feature was easier to see than the normal antics, requiring the user to simply change the system clock to the chosen day.