Power Rangers Zeo is a television series and the fourth season of the Power Rangers franchise, based on the 19th Super Sentai series Chouriki Sentai Ohranger. It is the continuation of Mighty Morphin Power Rangers, which aired in 1996.^{[1][2][3][4][5][6]}

Power Rangers Zeo is the first season of Power Rangers to follow the Super Sentai practice of annual Ranger suit changes.

After witnessing the destruction of the Command Center, the powerless Rangers discover the Zeo Crystal intact in the rubble—apparently dropped by Goldar and Rito Revolto. The Crystal guides them to a portal which takes them deep underground to the Power Chamber where they find Zordon and Alpha 5 waiting for them. The Mighty Morphin Power Rangers become the Zeo Rangers, a new team of Rangers powered by the Zeo Crystal. The four remaining Mighty Morphin Power Rangers, Tommy Oliver, Adam Park, Rocky DeSantos and Katherine Hillard become Zeo Ranger V — Red, Zeo Ranger IV — Green, Zeo Ranger III — Blue and Zeo Ranger I — Pink respectively and Tanya Sloan joins the team as Zeo Ranger II — Yellow, while Billy Cranston chooses to become their technical advisor rather than continuing as a Ranger.^[7]

The Machine Empire, led by King Mondo and Queen Machina, enters Earth's solar system, seeking to conquer Earth, with the Zeo Rangers serving as the only opposition. Many, even Rita Repulsa and Lord Zedd, are forced to flee to the M51 Galaxy under the threat of destruction. Unbeknownst to anyone, Rito and Goldar – now amnesiac – are left behind on Earth. They are taken in by Bulk and Skull, who have them serve as butlers. Meanwhile, Bulk and Skull continue to be members of the Junior Police Force until Lt. Jerome Stone is dismissed when Bulk tries to win the heart of the chief's daughter. Quitting as a show of respect for Stone, they join him at his new detective agency.^[8]

Over time, the Machine Empire wears down the five Zeo Rangers, but they are rescued by the mysterious Gold Ranger. Though his identity is unknown, it quickly becomes clear he is there to help the Rangers. After he is injured in battle, it is revealed that the mysterious Gold Ranger is an alien, Trey of Triforia. Split into three separate selves, Trey is forced to temporarily pass his powers to a worthy warrior while healing. They attempt to transfer Trey's powers to Billy, but as Billy acquired excess negative energy during the Command Center's destruction, he is unable to do so. Ultimately the successor is Jason Lee Scott, the original Red Power Ranger and team leader. This event also sees the introduction of the more powerful Super Zeo Zords, which are used against a tougher generation of machines. The Super Zeo Megazord is powerful enough to later destroy King Mondo, creating a power vacuum in the Machine Empire.

Secretly returning from the M51 Galaxy, Lord Zedd and Rita seek to take power again. Operating out of an RV with Finster, they restore Goldar and Rito's memories, retrieving the pair in the process. After King Mondo's death, they launch their first plan, to use Louie Kaboom to take over the Machine Empire. Though he succeeds, he breaks free of Zedd and Rita's control. He embarks on his own plans to conquer Earth and destroy the Zeo Rangers. Louie is eventually killed by King Mondo's first-born son Prince Gasket and his wife Princess Archerina, who rule until King Mondo's reconstruction is complete, which causes them to flee.

When Billy begins rapidly aging as a side-effect of restoring his proper age before undoing Master Vile's spell in the last series, the Zeo and Aquitian Rangers race to help him and fend off monsters from King Mondo as well as Zedd and Rita. Billy leaves Earth for treatment on Aquitar and chooses to stay to be with Cestria. Soon after, it is discovered the Gold Ranger powers are leaving Jason and draining his life force in the process as the alien powers were not meant for a human. Trey is still in recovery, but a risky gamble with the Zeo Crystal heals him, restoring his powers. Rita and Lord Zedd finally get revenge on the Machine Empire by crippling their leaders with a bomb.

Zeo Rangers

• Jason David Frank as Tommy Oliver
  He is Zeo Ranger V - Red and was previously the Mighty Morphin Green Ranger, the Mighty Morphin White Ranger, and the White Ninja Ranger. He found his Zeo Crystal in the American Southwest. He is the leader of the Zeo Rangers. Tommy wears a red suit with a star-shaped visor on his helmet. He piloted Zeo Zord 5, Super Zeo Zord 5, and the Red Battlezord. His primary weapon was the Zeo Power Sword.
• Johnny Yong Bosch as Adam Park
  He is Zeo Ranger IV - Green and was previously the second Mighty Morphin Black Ranger, and Black Ninja Ranger. He found his Zeo Crystal in Korea. Adam wears a green suit with a rectangular visor. He piloted Zeo Zord Four and Super Zeo Four. His primary weapon was the Zeo Power Hatchets.
• Steve Cardenas as Rocky DeSantos
  He is Zeo Ranger III - Blue and was previously the second Mighty Morphin Red Ranger, and Red Ninja Ranger. He found his Zeo Crystal in Mexico. Rocky wore a blue suit with a triangular visor on his helmet. He piloted Zeo Zord Three and Super Zeo Three. His primary weapon was the Zeo Power Axes.
• Nakia Burrise as Tanya Sloan
  She is Zeo Ranger II - Yellow and the only new member of the core group. When Aisha Campbell, the former Mighty Morphin Yellow Ranger, went for her Zeo Crystal in Africa, she decided that she wanted to help the animals who were sick; so she sent Tanya back with the Zeo Crystal in her place. Initially returning as a child, the Zeo Crystal made Tanya the same age as the other Rangers, which she gradually got used to. Tanya wears a yellow suit with two horizontal lines for a visor on her helmet. She piloted Zeo Zord Two and Super Zeo Two. Her primary weapon was the Zeo Power Clubs.
• Catherine Sutherland as Katherine "Kat" Hillard
  She is Zeo Ranger I - Pink and was previously the second Mighty Morphin Pink Ranger, and the Pink Ninja Ranger. She found her Zeo Crystal in her homeland of Australia. She is also Tommy Oliver's love interest. Katherine wears a pink suit with a circular visor on her helmet. She piloted Zeo Zord One and Super Zeo One. Her primary weapon was the Zeo Power Shield.
• Brad Hawkins (voice) and Ted, Tim & Tom DiFilippo as Trey of Triforia
  The original Gold Ranger and also the lord of planet Triforia, a place where everyone had identical triplets. He gave the Zeo Rangers their Super Zeo Zords when he had to return to his planet. Trey of Triforia wears a black suit with a golden vest and had a visor shaped like the kanji for "king". He piloted Pyramidas and his primary weapon was the Golden Power Staff.
• Austin St. John as Jason Lee Scott
  The second Gold Ranger and previously the original Mighty Morphin Red Ranger. When Trey of Triforia had to return to his planet, Tommy went and found Jason to take the place of the Gold Ranger while he was gone. He piloted Pyramidas and his primary weapon was the Golden Power Staff.

Supporting characters

• Robert L. Manahan as the voice of Zordon
  The Zeo Rangers' mentor. Zordon serves as a source of vast wisdom and knowledge for the team.
• Richard Steven Horvitz (credited as Richard Wood) as the voice of Alpha 5
  Zordon's robotic assistant, in charge of keeping the Power Chamber working.
• David Yost as Billy Cranston
  The former Mighty Morphin Blue Ranger and Blue Ninja Ranger, Billy has retired from being a Power Ranger, electing to instead assist Alpha.
• Richard Genelle as Ernie
  The owner of the Angel Grove Youth Center and juice bar.
• Paul Schrier and Jason Narvy as Bulk and Skull
  Former bullies who are initially junior police officers and then private detectives.
• Gregg Bullock as Lt./Det. Jerome B. Stone
  Jerome is a police lieutenant who is the supervisor of Bulk and Skull. After Bulk had a crush on his superior's daughter, he was fired. Jerome later became a private investigator with Bulk and Skull still working under him.
• Lesley Tesh-Pedersen as Emily
  A waitress at Ernie's Beach Club and a love interest to Jason.
• Erik Frank as David Truehart
  Tommy's brother, who was adopted by the same Native American (Sam Truehart) Tommy met while retrieving his piece of the Zeo crystal.
• Derek Stephen Prince (uncredited) as the voice of Auric the Conqueror
  An ancient tiki that had been dormant on the tropical Mysterio Island for years.

Villains

• Machine Empire
  • David Stenstrom as the voice of King Mondo
    The ruler of the Machine Empire.
  • Alex Borstein as the voice of Queen Machina
    The queen of the Machine Empire.
  • Barbara Goodson as the voice of Prince Sprocket
    The son of King Mondo and Queen Machina.
  • Oliver Page as the voice of Klank
    A robot that is loyal to King Mondo and Queen Machina.
  • Barbara Goodson as the voice of Orbus
    A floating module that is paired with Klank. When swung around by Klank, Orbus will make a monster grow.
  • Lex Lang (uncredited) as the voice of Louie Kaboom
    A missile-themed robot that was originally used by Lord Zedd and Rita Repulsa to take control of the Machine Empire following King Mondo's apparent destruction only for Goldar and Rito to lose the remote control. He can transform into his missile form.
  • Douglas Sloan (uncredited) as the voice of Prince Gasket
    Disowned older son of King Mondo and Queen Machina.
  • Melora Harte (uncredited) as the voice of Princess Archerina
    The daughter of King Aradon who eloped with Prince Gasket.

• Evil Space Aliens
  • Robert Axelrod (voice) and Ed Neil as Lord Zedd
    An intergalactic warlord. When the Machine Empire forced them off the Moon, Zedd worked to take revenge on the Machine Empire through whatever way possible.
  • Barbara Goodson (voice) and Carla Perez as Rita Repulsa
    An alien sorceress who became the wife of Lord Zedd. When the Machine Empire forced them off the moon, Rita worked to take revenge on the Machine Empire through whatever way possible.
  • Robert Axelrod as the voice of Finster
    The leprechaun-themed henchman of Rita. After the Machine Empire forced Zedd and Rita off the Moon, Finster was among those who were evacuated. He later returned with Zedd and Rita in a plot to take revenge on the Machine Empire.
  • Kerrigan Mahan as the voice of Goldar
    The manticore-themed minion of Rita Repulsa. He and Rito had amnesia following the Command Center's explosion and were roped into Bulk and Skull's plans until Lord Zedd restored their memories.
  • Bob Papenbrook as the voice of Rito Revolto
    The Gashadokuro-themed brother of Rita.
  • Michael Sorich and Dave Mallow as the voices of Squatt and Baboo
    Squatt is a hobgoblin-like minion of Rita and Baboo is a vampire-like minion of Rita. When the Machine Empire attacked Lord Zedd and Rita Repulsa's castle on the Moon, Squatt and Baboo were evacuated and remained with Master Vile while Lord Zedd and Rita Repulsa worked on ways to get revenge on the Machine Empire.
  • Simon Prescott as the voice of Master Vile
    The father of Rita and Rito. While allowing Rita and Zedd's group to take refuge with him, Master Vile noted that the Machine Empire was worse than he was.

Guest Stars

• Alien Rangers
  Rangers from the planet Aquitar, who helped protect Earth from Zedd and Rita during the events of the previous mini-series. They seek Billy's technological expertise at one point to help defeat new foes, and teach him about their own technology in return; thus creating the Red Battlezord.
• Paul St. Peter (voice) and Koichi Sakamoto (both uncredited) as Tritor
  A part-lizard alien who Bulk and Skull befriend when they are prisoners in the Machine Arena in "A King for a Day".

Starting in August 1996, several episodes of Power Rangers Zeo were released on VHS.

In 2012, Shout! Factory announced that it had reached an exclusive distribution deal with Saban Brands for shows such as Power Rangers and Big Bad Beetleborgs. Power Rangers Zeo was released on DVD in August 2012, as part of a Time-Life exclusive boxed set containing seasons 1–7. The show later became available independently of the boxed set in two volumes, each containing 25 episodes, released November 12, 2013, and February 11, 2014.

Image Comics began publication of a Power Rangers Zeo comic in August 1996. It featured scripts by Tom and Mary Bierbaum, and art by Todd Nauck and Norm Rapmund. Four issues were drawn but only one was released before Image Comics lost the license.^[11]

Characters have been featured in Power Rangers comics published by Boom! Studios.

In 2018, the Zeo Rangers appeared in "Shattered Grid", a crossover event between teams from all eras commemorating the 25th anniversary of the original television series. It was published in Mighty Morphin Power Rangers #25-30 and various tie-ins. A Power Rangers Zeo story by Kyle Higgins and Marcus To was published in Mighty Morphin Power Rangers 2018 Annual as part of the crossover.

"Beyond the Grid," the follow-up to "Shattered Grid", was published in Mighty Morphin Power Rangers #31-39. It saw Tanya joining a new team alongside the Ranger Slayer, the Magna Defender, Cameron, Andros and the Dark Ranger.

• Chouriki Sentai Ohranger