H.E.A.T.

Godzilla on the Empire State Building as depicted in the opening to Godzilla: The Series.

• Godzilla (vocal effects by Frank Welker) – A giant mutated iguana kaiju and the only surviving offspring of the first Godzilla that attacked New York City in 1998. Due to Nick's accidental presence at his hatching, Godzilla has imprinted on Nick as his parent and as a result, he is very protective of him. Nick also has the ability to control Godzilla to a certain extent, which allows humans to use him as a weapon against other giant and mutated monsters. He always seems able to sense whenever Nick is in trouble and is quite willing to follow him and the rest of H.E.A.T. all over the world. Unlike his biological parent, he seems to be incapable of asexual reproduction but is capable of using the signature atomic breath. Frank Welker, who provided the additional vocals for the character in the 1998 film, reprised his role as the titular character.
• Dr. Niko "Nick" Tatopoulos (voiced by Ian Ziering) – Leader of H.E.A.T. and the "adoptive father" of Godzilla. Nick fiercely protects Godzilla and other mutations from both foreign and domestic governments. He is portrayed as younger and with longer hair than Matthew Broderick's character from the 1998 film as well as being less absent-minded.
• Dr. Elsie Chapman (voiced by Charity James) – One of the original members of Nick's team; a sarcastic, dry-witted, feisty, altruistic, and cynical palaeo-biologist. She specializes in studying the behavior of Godzilla and other mutations. She also has the tendency to be jealous of Audrey around Nick, leading to the two women to snark at each other. James takes over the role from film actress Vicki Lewis.
• Dr. Mendel Craven (voiced by Malcolm Danare) – The team's engineer and chemist. He is slightly cowardly (as his last name implies) and prone to numerous strong allergies, but is often resourceful. He is also enamored of Elsie. Although initially fearful of Godzilla, over the course of the series he comes to trust the monster as an ally. Danare reprises his role from the film.
• Randy Hernandez (voiced by Rino Romano) – An intern and expert hacker working under Nick, and is Godzilla's constant supporter like Nick. He calls Godzilla "the G-man" and sometimes "the big guy" and he has referred to him as "Mr. G" and "the Lizard King" each on one occasion. Hugely talented in various fields of technology, but extremely lazy, sarcastic, and somewhat laconic, he usually annoys Mendel by programming N.I.G.E.L. with different various personalities, all the while sharing a tight brotherly rival with Mendel. Randy has a crush on Monique but is always rebutted when he attempts to court her. The acronym H.E.A.T. originated with Randy, although he initially had intended it to stand for High-performance Environmental Attack Team.
• Monique Dupre (voiced by Brigitte Bako) – A French Agent of the DGSE specializing in hand-to-hand combat and infiltration. She is originally sent to have Godzilla killed but becomes a member of H.E.A.T. after being assigned to supervise Godzilla indefinitely. She generally seems cold and impassive, but proves capable of honour, courage, compassion and loyalty. She is very talented with martial arts, espionage, and marksmanship.
• N.I.G.E.L. (voiced by Tom Kenny) – Short for "Next Millennium Intelligence Gathering Electronic Liaison", N.I.G.E.L. is an analysis robot created by Mendel and reprogrammed by Randy to have various quirky voices from a Texas cowboy to a Shakespearean actor. A running gag on the show is that he is damaged or destroyed in every episode (except one, and that one only because he does not appear in it) presumably to be rebuilt or replaced later (evidenced by Craven's remark in the episode "End of the Line" that he should "just buy spare parts in bulk") in a concept that is similar to Kenny McCormick from South Park.

Supporting

• Major Anthony Hicks (voiced by Kevin Dunn) – Commanding officer of the Sandy Point Military Base in New York, who played a key role in the first Godzilla's death. Though he is at first skeptical of the second Godzilla, over time he develops a soft spot for the creature, whom he views as a hero. Dunn reprises his role from the film.
• Audrey Timmonds (voiced by Paget Brewster) – Nick's college sweetheart and somewhat untrustworthy girlfriend, whose career as a reporter often leads the two into conflict. Yet despite that, she's always been there for Nick whenever it involves his life and Godzilla's life. Brewster takes over the role from film actress Maria Pitillo.
• Victor "Animal" Palotti (voiced by Joe Pantoliano) – A Channel 8 News cameraman and Audrey's sarcastic working partner who is always willing to help her film Godzilla and the other mutations, alongside helping the H.E.A.T. team. He is also a happily married man and supportive of Nick and Audrey's relationship. Pantoliano takes over the role from film actor Hank Azaria.
• Mayor Ebert (voiced by Michael Lerner) – The cynical mayor of New York City who is determined to keep it safe from mutation-related threats. Lerner reprises his role from the film.
• Philippe Roache (voiced by Keith Szarabajka) – High ranking agent in the French DGSE. Roache led the team hunting down the first Godzilla and later sent Monique to kill the second, but relented when the creature saved lives. Szarabajka takes over the role from film actor Jean Reno.

Villains

• Cameron Winter (voiced by David Newsom) – A former classmate of Nick in college. He is a devious technological mogul whose desire is to control Godzilla for the furtherance of his ulterior goals. Smug and sadistic, Winter frequently taunts Nick and H.E.A.T. and often enacts various plans to keep Godzilla in line. He also knows how to cover up his acts and maintain his position, allowing him to avoid prosecution. At the end of the episode "Lizard Season," he has successfully sold his technology over to the US military.
• Dale, Bill, and Hank (voiced by Ronny Cox, Tom Kenny, and Bob Joles) – Three game hunters who came to New York to hunt Godzilla. Dale is the leader of the group, Hank is the middleman, and Bill is the idiot of the group. The three of them would usually try to hunt Godzilla which usually ends with them either being thwarted by H.E.A.T. or ending up in legal trouble. The hunters worked for Winter at one time using his mecha creations to hunt Godzilla for a while. Their names are a parody of the characters from King of the Hill, and their bumbling antics are comparable to The Three Stooges, of which they are even called as such by Winter.
• The Leviathan Aliens (voiced by Ron Perlman) – An ancient species of psychically powerful extraterrestrials. One of their spaceships, called the Leviathan, crashed on Earth sometime during the Cretaceous Period of the Mesozoic Era and remained hidden until modern times. They attempted to conquer Earth by using a tachyon transmitter to send mind-controlling signals to subdue the mutations in order for their alien race to invade the planet - including Godzilla and their cyborg mutation, Cyber-Godzilla (created from the carcass of the first Godzilla) - but were ultimately defeated by H.E.A.T and a freed Godzilla and forced to retreat, probably for good.
• Sidney Walker (voiced by Steve Susskind) - An electric bus maintenance worker who was undergoing a Theta wave therapy to cure his insomnia, but ended up in a coma-like state that eventually manifested his subconsioucs rage as the giant monster Crackler. It was through Randy's deliberate provacation that brought Walker's anger to his conscious mind, severely weakening the Crackler.
• Dr. Jonathan Insley (voiced by Nick Jameson) - Dr. Jonathan Insley is the main antagonist that appears in the episode "Future Shock." He is the creator of the D.R.A.G.M.A.s, indirectly responsible for an alternate future where his creations had not only killed Godzilla, but also all of the other mutations on Monster Island, creating an apocalyptic scenario where humanity is forced to hide underground. Upon being confronted back in the present, Dr. Insley insisted that he had altruistic motives in mind for the creation of the D.R.A.G.M.A.s.
• Alexandra Springer (voiced by Linda Blair) - Alexandra Springer is the main antagonist in the episode "S.C.A.L.E." She is the fanatical leader of S.C.A.L.E. (Servants of Creatures Arriving Late to Earth), a radical animal-rights group that believe that mutations are the next stage of evolution and must be protected. She and S.C.A.L.E. interfere when Godzilla and H.E.A.T. were attempting to capture Skeetra but were then arrested. She gave Audrey a S.C.A.L.E. pin for spreading their message, as she respected Audrey's press career. Even though it appeared that she had given up her agenda, Alex was able to post bail and then followed the H.E.A.T. Seeker to Monster Island as the pin turned out to be a tracking device. She and the other S.C.A.L.E. members then released the mutations, locking up H.E.A.T. along with Animal and Major Hicks, and had Audrey continue filming. Luckily, H.E.A.T. managed to escape, captured Springer's forces, and placed the mutations back in their habitats. Springer attempted to activate the island's self-destruct, but was arrested by the military. While in custody, she gave Audrey a CD and asked her to tell her story to the world. However, Audrey ultimately decided not to air it and threw her final cut of the tape into the fire.
• Milo Sanders (voiced by Stuart Pankin) - An obnoxious and reckless tour guide of "Monster Liner", he bothers Nick and H.E.A.T. and ends up putting his passengers in danger while Godzilla was fighting the Deep Dweller. He also invited some photographers who attempted to get pictures of Godzilla up close, but were attacked by the Deep Dweller and had to be saved by H.E.A.T. While on board the H.E.A.T. Seeker, Milo sneaks down below and finds a tape that reveals the location of Godzilla's lair and loyalty to Nick. Seeing this as his one chance of fame, he plans to reveal to everyone Nick's secret. Audrey and Animal tried to stop him, but he escapes with the tape by stealing the H.E.A.T. Chopper. However, his attempt to reveal that the team was covering for Godzilla is cut short, when a news broadcast shows the police recovering the H.E.A.T. Chopper that he had stolen, resulting in his arrest as Animal had called up the same studio Milo was in.
• Dr. Alexander Preloran (voiced by Kenneth Mars) - A brilliant xenobiologist who Craven idolizes. Preloran and his colleagues enter a sunken Leviathan ship, where Preloran decides to help them conquer Earth, believing it will help the planet. He ultimately sacrifices himself by launching an escape pod manually so H.E.A.T. and his colleagues can escape, though Preloran soon discovers a doorway flooded with light and enters it, leaving his fate ambiguous.
• Tobias Wilson (voiced by Dorian Harewood) - A ringmaster of the mutant circus "Mutant Mania", he put a bounty on Godzilla, but Nick and H.E.A.T. saved Godzilla from the bounty hunters. Later, Nick confronts him for his bounty on Godzilla, telling Wilson to leave Godzilla alone or he'd do everything in his power to shut down Mutant Mania. When Medusa, a mutated Sea anemone escapes and starts wreaking havoc in New York, Wilson tried to stop Mayor Ebert from destroying Medusa on the claim of "private property," but the mayor refused. After Godzilla defeats Medusa and she's vacuumed up into an oil skimmer, Wilson attempted to flee with her only to be caught by the military.
• Colonel Charles Tarrington (voiced by Michael Chiklis) - A US Army colonel who is heading a project overseeing the creation of mutant scorpions for weapons. After the first scorpion proves uncontrollable, he has a group of smaller, more controllable scorpions created. Having a high disregard for Godzilla and other mutations, Tarrington appears to see the error of his ways after Godzilla destroys the scorpions, but orders a new batch of scorpions created immediately after, still intent on using them in spite of being nearly killed by the earlier waves.
• Paul Dimanche (voiced by Jesse Corti) - A corrupt business owner who was overfishing a Louisiana bayou and leaving the locals hungry. He begins flirting with Audrey when she interviews him over alleged abuse of over-fishing and illegal dumping into the swamps, of which he denied at first. He showed no care or concern for the safety of his guests when the Swamp Beast attacks his boat and mansion during Mardi Gras. After he was saved by Georges, he confessed to committing bribery which was unknowingly to him filmed by Animal.
• Dr. Hugh Trevor (voiced by Roddy McDowall) - A scientist who was studying Nessie the Loch Ness Monster, but wants to destroy it for attacking his lab. It is later revealed he kidnapped Nessie's baby and plans to sell it on the Black Market. Hoping to silence H.E.A.T. as soon as they found out about Nessie, he quickly tries to hide his motives from them, before attempting to drown Nick and Randy as soon as they confront him about Nessie, Jr. He then tries to escape with baby in tow inside his submersible, but Randy broadcasts Nessie, Jr.'s cries over the PA system, causing Nessie to catch Trevor's submersible. It is unknown what happened to him after Godzilla frees Nessie, Jr. from its cage, as Trevor is never seen nor mentioned again after being tossed aside by Nessie while still in his submersible.
• Maximilian Spiel (voiced by Clancy Brown) - A wealthy businessman and illegal fight promoter who also sets up a monster fighting tournament on a private island for other wealthy attendees. Audrey and Animal had been investigating his crimes in an effort to expose him, which puts him at severe odds with her and H.E.A.T. After the team, Audrey, and Animal are discovered having snuck on to his private island, Spiel attempts to have them killed by the mutations he had imprisoned. Turnabout comes when a freed Godzilla tosses the Giant Water Beetle up to the control tower and the Beetle lands on top of Spiel, trapping him.

Mutations

• Crustaceous Rex
• El Gusano Gigante
• Crackler
• Quetzalcoatl
• Loch Ness Monster
• Giant Bat
• Cyber-Godzilla
• King Cobra
• Ice Borers
• Mutant Termites
• Black Widow Spider
• Chameleon
• Techno-Sentient
• Jellyfish
• D.R.A.G.M.A.
• Skeetera
• Medusa
• Deep-Dweller
• Reptilian

Series overview

Season 1 (1998–99)

Season 2 (1999–2000)