Afterlife's "New" Number 17
A new Android created by Dr. Gero and Dr. Myu in hell. His origin obviously isn't human so he is pure evil and can control Android 17 to some extent by linking with his mind.
Baby
The Prince of the Tuffles, Baby saved himself before the destruction of his race by the Saiyans . . . well, his consciousness anyway. After his re-birth, he travels around the universe, possessing people by jumping in their body, trying to track down the last of the Saiyans. He comes across Goku, Trunks, and Pan and after a short battle, is thought defeated, but when Goku and the gang return to Earth, there's a surprise waiting for them.
Dark Shenron
A blue and black, overweight, cigar-smoking dragon who takes the place of Shenron when the minus energy in the Dragon Balls is at its peak. He appears briefly and then splits into the seven Evil Dragons.
Dr. Myu
Created by Baby to resurrect him, Dr. Myu is DBGT's equivalent of Dr. Gero. Dr. Myu (and the viewer) are under the assumption that Dr. Myu is trying to "create" Baby, when in fact, the doctor is a robot creation himself made by Baby to gather energy for his re-birth. Later in the series, Dr. Myu allies with Dr. Gero in hell and they create Afterlife's Android 17.
Doll Tokii
The true leader of the Ruudo Cult, an organization which is really just a front for gathering energy for Baby. He has a sick desire for little girl dolls. When Pan is turned into a doll, he takes her for himself.
Domma
Len's husband who isn't pleased with giving his wife to Zuunama. He wants to fight Zuunama with Goku, Trunks, and Pan.
Don Kiaa
A flashy dresser who rules the Planet Imegga with a limp fist! Everything on the planet is leased from him, making life for the common citizens extremely difficult.
Five-Star Shenron
A small Dragon who increases his size by absorbing electricity.
Four-Star Shenron
This Dragon is the "least" evil of the crew. He fights with honor. This is perhaps because he represents Goku's grandfather's spirit. Based on fire, he is able to power up and become a gold version of himself, capable of generating heat greater than that of the sun! He is always at odds with his brother, the Three-Star Dragon.
Geeru
Don Kiaa's male lackey. He's short and looks like a semi-shaved gorilla. He can perform weak ki attacks with Shira, but they're very weak in comparison to anything Goku can do.
General Rirudo
The second in command of the Machine Mutant Army, beneath Dr. Myu. He is fairly powerful, but nothing Goku can't handle. When so inclined, he can seal anything in steel a la Han Solo in carbonite.
Gettoo
A giant sword-wielding lizard that works for Panba.
Gill
A robot Trunks finds on the first planet they land on. Gill can locate the Dragon Balls because he ate the Dragon Radar to absorb energy. His relationship with Goku and Trunks is fine and dandy, but Pan seems to have a problem with the little robot. She's always yelling at the poor thing, but deep down she likes the little guy as a friend. His real name is G2006.
Great Monkey Baby
When Bulma focuses the Earth's Brute Waves directly at Super Vegeta Baby 2, he is able to transform into the Golden Great Monkey. He is a match for Super Saiyan 4 Goku and is able to control his thoughts and communicate with Goku while in the state. He is lethal and meets Goku's powerful attacks every time. Eventually, a different method of attack is used to defeat him.
Gull
Mishe's little seagull friend
Hyper Mega Rirudo
General Rirudo's form is perhaps the most devastating. He is, in essence, the entire M2 planet. Very similiar to T-1000, he is like liquid metal and controls anything he makes metal, entire forests are used against Goku as a weapon.
Lenn
A young woman offered to Zuunama as a bride in order to prevent him form causing earthquakes. Trunks impersonates her and takes her place when Zuunama comes for her hand in marriage.
Leon
A gigantic lion robot with huge manacing fangs. An appetite thirsty for blood. And it's defeated in 3 seconds by Goku who blasts a giant boulder on it.
M2 Commandos
The seemingly endless army of Machine Mutants who inhabit Planet M2.
Mega Cannon Team/Super Sigma
Naato, Ribeto, Biisu, and Nejji are four special robots in the Machine Mutant Army that can combine into the powerful Super Sigma 1/2/3.
Mishe
A young boy in a fishing village who is the only one who believes Princess Oto is a fake.
Moochii
The Cardinal of the Ruudo Cult. His weapon is a nasty whip that changes living beings into dolls. He gives the dolls to Ruudo to increase its energy. At the same time, he's also trying to gather the Dragon Balls, which he hires the Para Para brothers to do.
Muuchii
The robotic High Priest of the Ruudo Cult that disguises itself as a whip, the same whip that Moochii used. His arms are giant spiked whips that he can generate huge amounts of force with. And any inanimate object that his whips touch, he can control. Goku turns Super Saiyan as a kid for the first time when fighting this villain.
One-Star Shenron
The most powerful enemy in Dragon Ball GT, One-Star Dragon is more than a match for Super Saiyan 4 Goku. The battle against him is long and full of surprises. He manages to take on Vegeta, Gohan, Goten, and Trunks all at once by himself. But he is defeated in the end by Goku and the biggest Spirit Bomb ever, created with the power of the people on Earth, and everyone Goku met in the universe!
Pakku
Goku Jr.'s school bully who ends up befriending him on his journey.
Panba
A devilish witch that disguises herself as a pretty lady offering Goku Jr. and Pakku shelter, but deep within her lair, she prepares to kills her guests and eat them.
Para Para Brothers
Three brothers (Bon Para, Don Para, and Don Para) who use their rather unique dancing and music style to control their victims, making them susceptible to attack, or rob.
Paris
Goten's beautiful but . . . somewhat airy girlfriend. She has a kind heart and seems to really love Goten, but she's a ditz. In the first scene we meet her, she asks Gohan how to eat an ice cream cone.
Poperu
The boy Pan goes on a date with in the first episode of Dragon Ball GT.
Raccoon Family
A father and son who are very skilled at shape shifting. They're working against Goku in the Suugorou game disguised as the dice he rolls, but he befriends them later.
Rakkaru
Another sword-wielding animal who works for Panba. Rakkaru is a rooster.
Rejiiku
The only person Don Kia fears is this quiet and powerful alien. Words cannot describe his appearance, but his skin is similiar to a blue version of Cell's. He battles Goku for the challenge and finds himself beaten easily, he accepts defeat gracefully.
Robot Scientist
A "defective" robot scientist that befriends Pan and helps her around M2's maze-like interiors.
Ruudo
A giant doll-type robot. It is raised from a statue state when enough energy is gathered to operate it. It attacks Goku and Trunks viciously with huge spinning arms. When Pan is absorbed into the robot, it powers up and fights back even stronger.
Seven-Star Shenron
This Dragon is actually a creature that takes the form or powers of whatever it absorbs. And this Dragon absorbed a mole. So basically he's a giant tunneling Dragon . . . right. Although a pushover at first, he absorbs Pan! He becomes one of Goku's toughest opponents yet both physically and mentally for fear of injuring Pan.
Shira
Don Kia's female lackey. She can perform weak ki attacks, but her purpose doesn't seem to be fighting. She mostly takes care of whatever task Don Kia wants done at the moment.
Six-Star Shenron/Princess Oto
Disguised as a beautiful princess, this is actually the Six-Star Dragon. He is able to spin at an incredibly high velocity that helps him by, creating the illusion of the princess, and deflecting attacks!
Son Gokou Jr.
Goku's great-great-grandson! He lives with his grandmother Pan and the legend of Goku and what he did is nothing but stories to him. He's a clutz and a wuss. At school he's constantly tormented. Picture Goku, without any strength, and this is basically what you get. But like Goku, he has a good heart and is a fine person. He goes on a journey into the Paozu Mountains to track down the Dragon Balls in order to wish his Grandma back to health.
Super Saiyan 4 Gogeta
Arguably the most powerful character . . . ever. The result of fusion between Super Saiyan Goku 4 and Super Saiyan Vegeta 4, this is not a guy to be messed with. His special attack is Big Bang Kame Hame Ha. Unfortunately, he suffers from the cockiness of fusion, which always happens, and wastes his time without actually killing One-Star Dragon.
Super Hell Fighter 17
When Afterlife's "New" Android 17 and Android 17 combine, they become this threatening villain. Capable of making Vegeta's ultimate ki attack nothing, he is truly a perfect villain because he actually absorbs all attacks and they make him stronger. Number 18 and Goku defeat him together. White 17 is distracted by 18's continuous energy blasts, Goku shoots through his torso with Dragon Fist, destroying his ability to absorb attacks. Then Goku unleashes a fury of Kamehamehas and destroys him.
Suugorou
A "master" of the game Suugorou. He battles Goku for his freedom from the game, but has to win. Only problem is, Goku never gets a good roll from the dice. But Suugorou seems to do fine every time.
Three-Star Shenron
This ice-based Dragon is Four Star's brother (Get it? Fire and Ice?). He's a dirty fighter and the complete opposite of his brother. Four-Star actually assists Goku in the fight against him.
Two-Star Shenron
A wimpy Dragon with a devastating special talent. His body emits minus energy that infects a lake making it rancid and devoid of life. Everything around him reacts the same way. Pan doesn't take him seriously at first and fights half-heartedly, something that would have been an easily won battle. But over time, she and Goku become weak and eventually can't move, at which point they're hurled to the bottom of the lake to drown . . .
Vegeta Baby
After controlling Goten and Gohan, Bebi uses them to fight against Vegeta. When they injure him, Baby enters Vegeta's body through wounds and takes control of him. From here, Baby takes control of everyone on Earth except Uub, Mr. Boo, and Mr. Satan. He has a total of three normal forms. He reaches these levels by absorbing power from people (and Saiyans) on Earth. His third stage is the most well-known as it is his most powerful normal form.
Youmaou
A giant demon boar who rules Panba and her crew. When Goku Jr.'s anger rises up, he defeats this giant creature and his crew, proving that he's definitely a relative of Goku!
Zuunama
A giant walking catfish monster who terrorizes. He can cause earthquakes with his huge whiskers. But his claim to fear isn't all it's cracked up to be.
Source: Beckett Dragon Ball Z Collector, Sept. 2001, Issue 10, by Greg Werner.