TigerSharks

Protectors of Water-O, the team members are:

• Mako (voiced by Peter Newman) - A gifted scuba diver, he is considered the field leader of the TigerSharks. Mako is not only a good mediator, but also an excellent fighter. He transforms into a human/mako shark hybrid, which grants him incredible speed underwater. Mako also uses his forearm fins and head fin to slice through metal.

• Walro (voiced by Earl Hammond) - The scientific and mechanical genius who created the Fish Tank. He acts as the advisor of the team and is very respected by his comrades. Walro turns into a human/walrus hybrid. He wields a cane that has a wide variety of weapons.

• Rodolfo "Dolph" (voiced by Larry Kenney) - Second-in-command and also an experienced scuba diver. Dolph has a knack for jokes and fooling around, but he knows when to joke and when to work. Dolph turns into a human/dolphin hybrid, which makes him very maneuverable underwater and can shoot a strong jet of water from his blowhole. However it also makes him the only Tigershark unable to breathe underwater in his aquatic form. He speaks with an Irish accent.

• Octavia (voiced by Camille Bonora) - Captain of the SARK, communications technician and main strategist. Octavia turns into a human/octopus hybrid (with tentacles instead of hair).

• Lorca - The team's mechanic and often helps Walro to repair or build new machines. He's also the team's strongest member and was the one who invented the Fish Tank. Lorca turns into a human/orca hybrid. He speaks with an Australian accent.

• Bronc - A teenager who, along with his sister Angel, works as an assistant aboard the SARK. Bronc is very adventurous, and sometimes reckless. He turns into a human/seahorse hybrid, hence his name, which is derived from "Bronco".

• Angel - Another teenage member of the SARK's crew. She's more serious and responsible than her brother. She turns into a human/angelfish hybrid, hence her name.

• Gupp - The TigerSharks' pet Cocker Spaniel. While his name might imply that he turns into a guppy, his features, including flipper-shaped legs and pin teeth, more closely resemble a seal or sea lion.

• SARK A.I. - The artificial intelligence of the SARK.

The show featured two major antagonists, both with teams of followers. Both are in alliance to conquer Water-O and destroy the TigerSharks, but plan to betray each other once these goals are met. They are:

• The Mantannas - A race of alien sea creatures who arrived on Water-O after their home planet dried up.
  • T-Ray - T-Ray is a human/manta ray hybrid-type creature and the leader of the Mantannas. In seeking to conquer Water-O, he freed Captain Bizzarly and his crew from their iced prison on Seaberia. He is bent on conquering the Waterians and destroying the TigerSharks. He and his assistants cannot survive outside the water without using water breathing apparatus. He wields a whip.
  • Wall-Eye (voiced by Peter Newman) A human/frog hybrid who is T-Ray's aide-de-camp. He can hypnotize people by spinning his eyes.
  • Shad - A bad-tempered human/grouper hybrid. He wears a belt that can shoot electrical blasts.
  • Dredge - A human/eel-like mutant who carries a purple pet eel on his back.
  • Carper and Weakfish - Two merman with frog-like faces. Identical twin brothers who (as befitting their names) whine and complain about everything. Carper has green skin while Weakfish has purple skin.

• Captain Bizzarly - A pirate with aquaphobia who controlled all crime-related activities on the vast oceans of Water-O until the Waterians froze him and his crew in ice many years ago. T-Ray freed Bizzarly and his crew expecting them to join forces. However, Bizzarly promptly betrayed T-Ray. Bizzarly now constantly tries to get rid of the TigerSharks and regain control of the oceans of Water-O.
  • Dragonstein - A sea dragon-like creature who is Captain Bizzarly pet and bodyguard. He can fly, breathe fire, and maneuver underwater.
  • Long John Silverfish - A humanoid with fish-like features. He wields an electrified whip.
  • Spike Marlin - Bizzarly's first mate, a wrinkly-faced human wielding a customized polearm.
  • Soulmate - The only female member of Captain Bizzarly's crew. Her attire suggests a samurai. She wields a sword, among other weapons.
  • Lump - A slimy, shapeshifting blob-like creature.
  • Grunt - An overweight humanoid who grunts like an ape and is the largest of the pirates. He's the muscle of Bizzarly's crew.