Prince Planet is the English-language title given to one of the earliest anime television series, Planet Boy Papi (遊星少年パピイ, Yūsei Shōnen Papī), when it was transmitted on American television in the United States in the mid-1960s. It did run on "The Works" television network before it ceased operations February 28, 2017. A 52-episode monochrome anime series, it tells the story of a member of the Universal Peace Corps, originally from the planet Radion, coming to Earth on a mission to determine if this world meets standards for membership in the Galactic Union of Worlds and assist its inhabitants during his stay. While on his mission, Prince Planet adopts the identity of an Earth boy named Bobby and gains comrades who work together alongside him fighting forces of evil, both alien and terrestrial.

Prince Planet was originally produced by TCJ (Television Corporation of Japan, now Eiken) and aired on the Fuji Television network in June 1965. The show was one of the first heavily merchandised shows in Japan, with simple things like shoes getting the "Planet Boy Papi" logo. An English-dubbed version was released by American International Television Productions in September 1966, and produced by James Nicholson and Samuel Z. Arkoff. The dubbing was performed in Miami at Copri Films International and directed by Mark Harris, with dialog scripting by Reuben Guberman, who also reworked The Amazing 3 for Erika Productions in 1967 and developed the live-action tokusatsu-kaiju series Giant Robo for American television, later that same year, under the title Johnny Sokko And His Flying Robot. The American theme was composed by Guy Hemric and Jerry Styner, who had previously written songs for several of American International's "Beach Party" movies. Glico was a major sponsor for the series and made Papi "prizes" that came in certain candy products. Prizes included mini action figures and play jewelry.

The main characters appearing throughout most of the series are all introduced by the fourth episode. In episode 1, Prince Planet arrives on Earth and meets a girl, Riko or Diana Worthy in the English-dubbed version and her father, Pops Worthy, who live on a large ranch. In episode 2, a wrestler known as Dan Dynamo, billed as "The strongest man in the world," joins the Prince Planet team. Episode 3 introduces Warlock, who is said to be the "Master of Martian Magic," although his Martian origins seem to be more of a contrivance added to the English dub; whatever Warlock's origin, he is established as a student of some kind of magical school who runs away to Earth after being punished for getting drunk on prune juice. The last major team member is a magician named AjiBaba of Abbadon, from the desert of the eastern hemisphere who debuts in episode 4 as an arch-enemy of Warlock, who attacked his country. Many of the episodes involve battles with Warlock until episode 30, when Krag from the planet Kragmire banishes (throws) Warlock into the depths of space and becomes Prince Planet's major nemesis until the end of the series. Warlock finally returns in the second-to-last episode of the series.

While on Earth, Prince Planet exists usually as Bobby, a normal boy, but when the need arises he will transform into Prince Planet to fight enemies or protect his friends. He transforms similarly to Shazam by holding his pendant with both hands and saying "Peeeeeee Pazow!!" with the "Pazow" being added to cover the Japanese "Papi." When Bobby is transformed into Prince Planet, an appropriate suit of battle armor comes with the transformation, armor which resembles the apparel worn by the people of his native world. This includes a helmet, which all male members of Radion society seem to wear.

Prince Planet's main powers are not altogether unlike those of Superman, and in the original Japanese, his home world is named "the planet Crifton." His pendant-endowed powers include super strength, flight, and resistance to harsh environments like outer space, though he can be injured in his transformed state. Prince Planet can also use his superior intellect (in several episodes, he is said to have an IQ of 200) along with the energy of the pendant to transform material objects at will; this power is very useful to create needed weapons, transportation, or other devices.

A recurring plot element of many episodes hinges on a limitation resembling that of the Green Lantern of DC Comics, in that his pendant needs to be recharged periodically, 24 hours for the Green Lantern and an entire week for Prince Planet. But unlike the Green Lantern, Prince Planet cannot perform this task himself. Instead, replenishment of the pendant's energy is handled from the planet Radion. As his energy supply diminishes, the "P" in his pendant goes from black to white like a thermometer in dropping temperatures.

On Prince Planet's home planet of Radion, in the "power tower," there is a person whose job is to monitor the pendant's energy level and ensure that it does not run too low. Not surprisingly in view of this plot element, the custodian of the Radion power tower often appears to be "asleep on the job" while Earth and Prince Planet are hanging in the balance, and he sends energy to the pendant at the last possible second before disaster. Even whenever he has been completely deprived of the pendant's power, however, Prince Planet can still, physically, put up a good fight, and his high intellect makes him a cunning and formidable opponent.

Prince Planet was televised in Australia and aired in Melbourne in March 1967 on Channel 9 at 5pm weekdays. The series was well known in Australia. It last appeared on Australian television in 1974 on the Super Flying Fun Show, a weekday breakfast television series.