Number one: To read, Number two: Number two!
— Dr. Colosso
This is Dr. Colosso. He is as evil as they come. He boos at funerals.
— Max about Dr. Colosso
Dr. Colosso is a regular character on the Thundermans. He is a former supervillain who was turned into a pet bunny by Hank. He lives with the Thundermans and is Max's sarcastic pet bunny. Dr. Colosso is voiced and portrayed by Dana Snyder.
Dr. Colosso was born and raised in Metroburg. He became a powerful supervillain and even planned on marrying someone at the president's office but was eventually stopped by Thunder Man. Dr. Colosso later invented the Animalizer, an invention capable of turning humans to animals and vice-versa, to turn Barb and Hank Thunderman into goats and gave them a toaster as their wedding gift. Dr. Colosso was later defeated by Hank. Instead of turning in Dr. Colosso to the Hero League for prosecution, Thunder Man turned him into a bunny using the Animalizer instead as revenge for what Dr. Colosso did to Hank and Barb Thundermen. He became Max's pet.
Despite being defeated and turned into a bunny, Dr. Colosso did not abandon his evil ways. He continues to consider himself a supervillain. During Max's evil phase, Dr. Colosso quickly became Max's friend and coached him to become a supervillain. He "hates" the rest of the Thundermans and looks for every chance he gets to mock them.
In Pretty Little Choirs, Dr. Colosso got kidnapped by Darcy Wong after she discovered that he could talk. She tortured him to get him talking to prove that the Thundermans was weird but she wasn't successful. In the same episode, he told Nora and Billy that he hates it when they dress him up without letting him choose the costumes.
In Haunted Thundermans, he sneaked into Max's backpack so that he can go to New Orleans with the Thundermans. When the Green Ghoul possessed Phoebe and asked Max to join, Dr. Colosso persuaded Max to accept the offer but Max refused.
In Blue Detective, Dr. Colosso became so jealous of Max and Cassandra that he stole one of Max's blue beans and turned Max blue. When they later figured out it was him, he admitted that his only crime was loving Max ... plus all other his actual crimes.
In One Hit Thunder, Hank and Barb asked Nora and Billy to be nice to Dr. Colosso instead of stooping to a supervillain's level. The whole family tried being nice to him but he made their lives miserable. He told them he hates it when they're nice to him. He likes them to mistreat him because he's a supervillain and has nothing else to live for.
In A Hero Is Born, Dr. Colosso was invited to the Villain League headquarters to give the Villain of the Decade speech. After helping deliver baby Chloe, Max agreed to turn Colosso into a human using the Animalizer so that they can go to the Villain League together. However, on arrival, he found that King Crab, Lady Web and Scalestro lied about the award and the speech. They had lured him to kick him out of the league because he hadn't done anything evil in years. To save himself, Dr. Colosso betrayed Max and turned him into the other villains, saying that he had captured the son of Thunder Man. However, after looking at a selfie of him and Max, he felt guilty and went back to help Max. King Crab tied him up together with Max so that they can be eaten by the hermit crabs. They were later saved by Phoebe. Dr. Colosso turned back to a bunny because of the timer Max had put on the Animalizer.
In Are You Afraid of the Park?, Dr. Colosso needed to make some money to repay Hank the money he charged to Hank's credit card while playing Candy Squash online. So, he started running an unauthorized cereal business, selling a cereal called "Colosso's." He made enough money to pay the debt and got a surplus. However, his website got shut down by the Federal Bureau of Cereal Investigation. They said the cereal business was illegal and the raisins weren't really raisins. The Thundermans had to pay the fine.
In He Got Game Night, Dr. Colosso helped Max cheat the wheel of prizes so that it will land on a new car during the family game night. But Max turned on him so that he can partner with Allison. Dr. Colosso became jealous of Allison. Phoebe then turned him into a human to be her game night partner. He came in and introduced himself as "Uncle Colosso." Barb and Hank got furious at Phoebe for turning him human but allowed him to continue after realizing that Dr. Colosso and Max weren't going to let each other's team win. Unfortunately, Dr. Colosso quickly brought chaos into the family leading into an epic pillow fight. When Allison left, Barb quickly turned Colosso back into a bunny. Colosso then went outside and started eating away Allison's tires.
In Thundermans: Secret Revealed, Dr. Colosso gave Max the tuxedo he wore to evil prom with Octopus Girl. He was happy when Dark Mayhem finally called to give Max an opportunity to become a full supervillain. He tried to advise Max to use the orb to steal Phoebe's powers but Max was reluctant about it. Dr. Colosso was taken away from Max as a punishment for working with Dark Mayhem. However, he managed to escape and help Max out of the lair. Later, during a call with Dark Mayhem, Dr. Colosso realized that Dark Mayhem really hated him and would destroy him if he took over Hiddenville. So, he helped the Thundermans escape the house just before Dark Mayhem's attack.
In Thundermans: Banished!, Dr. Colosso is still mad because Max chose good over evil in Thundermans: Secret Revealed. When the Thundermans are banished to Antarctica, Dr. Colosso chooses to remain behind. However, after realizing that his new roommate, Candi Falconman wants to control people in Hiddenville, he calls Max and Phoebe to come and stop her; but plays along so that Candi doesn't suspect him. He later helps the Thunder Twins escape by eating away all the cotton candy binding them.
Since Max stopped being evil, Dr. Colosso's life has become difficult. In Smells Like Team Spirit, he complains about being fed with gross succotash and reveals that Max used to steal fresh vegetables for him. He takes advantage of Billy being gullible and sends him to steal fresh vegetables from other people's farms by claiming that he's the one who planted them. Nora and Chloe help Billy figure out that he's being tricked and they get back on Colosso by pretending that the cops are coming. Colosso tries to escape but gets busted by Chloe dressing as a police officer.
Without Max, Colosso now has time to speak to his mother. In Max to the Future, he spends most of his time on a call with his mother. He later helps Max to fake crimes to make Max's CrimeCaster look good. Unfortunately, he gets busted by Phoebe when he forgets and takes a call from his mother. In Parks & T-Rex, he even fakes being sick just to trick Max into hanging out with him. Max later finds out and promises to spend more time with him.
In Better Off Wed, it is revealed that Dr. Colosso invented the Animalizer back in Metroburg when he was still a human. He introduced it as "the people-to-animals switcherooni ray" when he crashed Hank and Barb's wedding. He wanted to ruin their wedding because Thunder Man and Electress had stopped his wedding at the Oval Office earlier. At first, Hank mocked the gadget, claiming that none of Dr. Colosso's inventions really work. Colosso then used the animalizer to turn Barb and Hank into goats and swore that he would never let Hank and Barb have a successful wedding. The Hero League later found a way to turn Hank and Barb back into humans. After that, Hank went after Dr. Colosso and used the animalizer against him, turning him into a bunny. When the Thunder Kids learn the story, they plan to throw their parents a new wedding but Dr. Colosso swears to ruin it again. He jumps into the kitchen counter where the animalizer is kept and turns himself human. He then crashes the fake Phoebe wedding and turns the Thunder Kids into animals. When Barb and Hank arrive at the wedding renewal, he tries to turn them into goats again. They defeat him and turn him back into a bunny. He officiates the wedding.
Following Allison's breakup with Max in 21 Dump Street, Dr. Colosso stays by Max's side, laying on the couch and eating pizza with him. However, when Molly sees him, she blames Max for mistreating a bunny by feeding him unhealthy food. So, she steals him for the Green Teens Pet Adoption Fair. Colosso is adopted by Principal Bradford, forcing Max and Phoebe to sneak into their school at night and steal him back.
Still mad at Max for turning good, Dr. Colosso has been getting revenge on Max and Phoebe whenever he gets a chance. In Z's All That, he refuses to tell them about the Li'l Z Program, causing them to be ranked last. He later helps Nora amplify her powers to confront Phoebe and Max for replacing her with Billy as their Li'l Z. In Nowhere to Slide, he gets revenge on both the Max and Phoebe by sabotaging their boys and girls nights because they had ditched him earlier. In Rhythm n' Shoes, he gets revenge on Max for taking credit as DJ Colosso. The sabotage involves hacking Phoebe and Cherry's rhythm shoes causing them to ruin Cheyanne's sabotage.
Colosso's stay at the Thundermans house is threatened in Make it Pop Pop when the villain-intolerant grandfather, Pop Pop Thunderman (Sergeant Thunder) comes to town and learns that Max has been hiding a supervillain like Colosso in his lair. The Thunder Twins try to help Colosso escape but Pop Pop gets a hold of him and throws him into the Detention Zone along with Max. Phoebe comes to try to save them. Ultimately, it's Colosso who saves them by providing evidence that the twins are Sergeant Thunder's grandkids. Colosso manages to escape back with Max and Phoebe. The twins convince their grandfather that Colosso is becoming a better person because of living with superheroes. Colosso then immediately insults Pop Pop, only to be knocked unconscious after Pop Pop drops the thunder on him.
As revealed in The Thunder Games, Dr. Colosso has a son named Balfour. Since Dr. Colosso couldn't parent Balfour, Balfour was raised in a super orphanage. When the Z-Force championships have a break, Balfour recognized him as his father due to the Hero League giving one of Colosso's cape. Balfour and Dr. Colosso get revenge on the Thunderman Family but Balfour is stopped by the Thunder Twins' twin power, a strong amount of energy. Balfour gets turned into a bunny and him and Colosso can finally bond together.
Dr. Colosso, being a former supervillain is filled with mischief and desire to be evil. He spends most of his time hating on the Thundermans or helping Max with his evil plans. You can never really trust Dr. Colosso on anything because he easily turns on people, even Max. He is very sarcastic and uses his sarcasm in every opportunity he gets. Despite his villain attitude, Dr. Colosso can be very soft and emotional sometimes especially when he's trying to get Max's attention.
- Main article: Max and Colosso
- Max is Dr. Colosso's owner and best friend. Before Max chose good, Colosso helped Max embrace evilness. Even though Max chose good, they have still been good friends.
- Both Dr. Colosso and Phoebe thinks poorly of one another and don't like each other at all. Colosso thinks she's annoying and they've been bickering at times.
- Dr. Colosso's former arch nemesis when they lived in Metroburg.
- Dr. Colosso ruined Hank and Barb's wedding as shown in Better Off Wed and ever since Colosso turned Barb and Hank into goats, the Hero League captured him and Hank decided that Colosso should be changed into a bunny as revenge on what he did to them.
- Colosso has a crush on Barb and wishes to take her away from Hank, even though Barb hates Dr. Colosso.
- Like in He Got Game Night, he was flirting with her when he turned human by Phoebe.
- He often plays with the Thunder Kids, Nora, Billy, and Chloe, and sometimes manipulates them like in Mad Max: Beyond Thunderhome. Nevertheless, Colosso plays dress-up with them as well as.
- He was formerly the strongest supervillain until he was turned into a rabbit by Hank.
- Dr. Colosso was originally going to be all white but was changed to black and white.
- Dr. Colosso gets freaked out by alarms and self-destruct.
- Dr. Colosso loves carrots.
- Dr. Colosso has superpowers but they were never seen in the show
- He has a stuffed animal called Teddy and plays with him when he's alone.
- Dr. Colosso once got eaten by Trevor, the Venus Flytrap plant, in The Weekend Guest.
- Dr. Colosso and Max have dance parties privately.
- He wears a lot of fun costumes.
- In the episode, Pretty Little Choirs, he was seen dressed as a princess and it was revealed that he hates playing dress up, except for dressing up as a lifeguard or a firefighter. However, he actually likes to wear costumes, as shown in many future episodes.
- In the episode, Crime After Crime, when Max was grounded after making everyone think he was the neighborhood vandal (as he didn't want anyone to know he couldn't ride a bike), Phoebe went to Max's lair to show him the consequences the Thundermans suffered. Dr. Colosso dressed up as s security guard and guarded the entrance to the lair with an airport x-ray machine.
- Billy and Nora like to dress him up.
- He gives fashion lectures, as mentioned in Come What Mayhem.
- He always had a black circle traced around-the-world style over his left eye.
- In the episode, Paging Dr. Thundermans, Dr. Colosso stated that he is a doctor and operated on a hundred people.
- In A Hero Is Born, Dr. Colosso delivered Chloe.
- In Blue Detective, it is revealed that Dr. Colosso is jealous of Max's girlfriend, Cassandra.
- In A Hero Is Born, Max turns Colosso human and accompanies him to receive the Villain of the Decade award.
- He was only absent in one episode — the hour-long special, Thunder in Paradise.
- This makes him the first main character on the show to be absent in an episode.
- Dr. Colosso appears in a Nicky, Ricky, Dicky & Dawn special, The Wonderful Wizard of Quads where he's being kept hostage by the evil witch as a punishment for using the slide without permission. He gets turned into soup.
- It is revealed in Nowhere to Slide that Dr. Colosso is 48 years old.