Peladon of Peladon (PROSE: Legacy) was the king of Peladon in the 39th century, when it was admitted to the Galactic Federation. He met and befriended the Third Doctor and Jo Grant in the final stages of establishing ties to the Federation.
Peladon was the son of King Kellian and the human Ellua, Princess of Europa. His father gave him the name "Peladon of Peladon" because it seemed to have "great flair and flourish", and would impressively announce his son on other worlds. (PROSE: Legacy)
Peladon wanted his planet to join the Federation, but Hepesh conspired against him, eventually taking the King hostage. Peladon was rescued by the Third Doctor and Jo Grant, whom he had fallen for, even proposing marriage to her, though she declined. (TV: The Curse of Peladon)
Five years after Peladon joined the Federation, Peladon opened Peladon to refugee Martians from the New Martian Republic, after the royal family on New Mars were overthrown and executed by Grand Marshall Raxlyr. Peladon invited the elder Martian, Lord Vaarnak, to be spokesman. A Martian ship had been sabotaged, crashing near the citadel. While rushing to find survivors, Peladon found a recently-arrived Third Doctor aiding them. The Doctor only intended a short visit, but King Peladon insisted the Doctor to stay to offer his counsel. Back inside the citadel, the Doctor discovered Lord Vaarnak had been murdered.
The morning after the Doctor saw a light from the citadel's tallest tower blink, Peladon investigated the light, feeling concern over the legend of the Prisoner of Peladon. He found the Doctor had also investigated the tower, and told him about the legend that lay behind the double doors with four locks. The Doctor realised Lord Axlaar was the murderer of Lord Vaarnak, whom had done so because his family had been dishonoured when Vaarnak didn't align with Grand Marshall Raxlyr. Vaarnak was also involved with the kidnapping of Martian orphans to find the missing princess, Lixgaar.
The Doctor realised that the four hands to operate the four locks to the Prisoner of Peladon's prison could have been operated by a lone hexapod, rather than two people in tandem — Alpha Centauri. He also figured out that Centauri, having access to the royal collection of relics, would have known where to find the keys and hid the Princess away. Lord Axlaar had initially intended to find the Princess with subterfuge, but upon being found out threatened to summon reinforcements.
The Doctor took King Peladon, Lord Axlaar and Axlaar's accomplice, Sslurn, to the chamber of the Prisoner. There, the Doctor knocked at the chamber doors, which Centauri opened from inside. The Doctor called for Princess Lixgaar within the chamber, whom Axlaar threatened with his sonic disruptor. The Doctor attacked Axlaar in the chest; the blast of the disruptor hitting Sslurn. Axlaar took aim again at the princess, swatting the Doctor aside, and King Peladon threw himself at him in a blind rage. After this, Axlaar fell from the window.
The Doctor tried explaining to Peladon that the death of Axlaar wasn't his fault, only for Peladon to chastise the Doctor for treating him like a child, treating the situation like a game and refusing to explain anything. The next day, Peladon returned the Martian girls Axlaar had kidnapped in the search for the princess to their families. The Doctor informed Peladon that Izlyr arranged a peacekeeping ship to take the princess to Io. The Doctor quietly left in the TARDIS while Peladon spoke with Centauri. (AUDIO: The Prisoner of Peladon)