The UnderWorld Tribe occupies most of the UnderWorld; most UnderWorlders are users of the fire element and intimidate their opponents to weaken their stats. The UnderWorld is led by Chaor who relies on commanders such as Takinom, Agitos, and Rothar. In the episode Lord of Treachery, it was made to seem that Van Bloot was a 'traitor' (even though a traitor is someone who was on someone's side first - it was never made clear whether Van Bloot was ever on Chaor's side as such) to Chaor and wanted to rule the UnderWorld himself, almost starting a civil war in the process.
Sworn enemies of the OverWorlders, most often they align themselves with the Danians by default as both tribes preside over the UnderWorld of Perim.
UnderWorlders focus on fire attacks with some earth attacks. As a default, most UnderWorlders have high strength and low wisdom.
UnderWorlders' main draw backs are their recklessness and wisdom. UnderWorld creatures usually have Recklessness 5 and sometimes Recklessness 10, making it unusual to win against creatures with high energy. Few UnderWorlders have high wisdom. They usually only dominate in power and sometimes courage. They don't have many Muges, and most UnderWorlders have few mugic counters.
The UnderWorld tribe is one of the main focuses of the TV show, just below The OverWorld. They where the first to lead a full scale attack on the M'arrillians. Their attack failed, leaving Chaor and several of his followers refugees. In the absence of its rulers, the UnderWorld quickly fell to the M'arillians, save but a few including Takinom. Chaor returned in the end of season two, fighting alongside Maxxor and Iparu against Aa'une.
- Further information: Category:UnderWorld Creatures
- Chaor - Leader of the UnderWorld
- Agitos - Chaor's advisor
- Atrapol - Leader of Lord Van Bloot's army and one of Van Bloot's strongest warriors.
- Barrath Beyond - A powerful UnderWorld warrior
- Borth-Majar - Brain and Brawn, respectively; Borth and Majar must fight as one.
- Chargola - An UnderWorld commander known for his meticulous planning.
- Dardemus - A very strong and mean prison guard of the UnderWorld.
- Grook - An UnderWorld Creature that resembles a round shark.
- Hammerdoom Chantcaller - A legendary UnderWorld warrior and enemy to the Danians.
- H'earring - An UnderWorld spy. He also shows his friend Kaz new scans in exchange for gross consumables, such as Dractyl scales.
- Jiggorex - Khybon's assistant
- Khybon - An UnderWorlder who invents and manufactures various types of UnderWorld BattleGear and works on expanding the caverns, passages, grottoes and pillars.
- Kiru - A Past Conqueror, he is Chaor's ancestor. was ruler of Past OverWorld.
- Krekk - An UnderWorld Scout and a bit of a coward. Torn between loyalty to Chaor and Lord Van Bloot.
- Lord Van Bloot - Classed as a traitor of Chaor, he wishes to rule the UnderWorld and Perim.
- Lyssta - A strong warrior in the UnderWorld Coliseum. She has lost only once...to Chaor.
- Magmon - An UnderWorld Elementalist made of lava and stone
- Narfall - An UnderWorlder who may have found the Cothica.
- Neerig - An UnderWorlder who is an ancestor of H'earring.
- Nauthilax - An UnderWorld Elementalist spy who is one of the only UnderWorlders that have water-elemental abilities and can swim. He explores underwater tunnels for Chaor.
- Pyrithion - A powerful UnderWorld commander who is very snake-like.
- Rarran - An Underworld Scout that resembles a bat.
- Rothar - One of the toughest and ruthless UnderWorlders in the show, but he is very loyal to all UnderWorlders.
- Skreeth - An UnderWorld warrior who is like a cross between a (typical) demon and a skeleton. He lives in puddles in Everrain and has a mean streak.
- Stelgar - An UnderWorld Minion Warrior that resembles a starfish. Stelgar was once a Tribeless Creature.
- Takinom - Chaor's most trusted ally and one of the most powerful warriors in the UnderWorld
- Ulmar - An UnderWorld scientist known for his creation of BattleGear and said to be a little insane.
- Ultadur - A UnderWorld commander known for his strength and speed.
- Chaotic shows all sides to the tribe war, so the UnderWorlders may sometimes be protagonists, or "Anti-heroes", when shown in a good light, opposed to the over tribes. Although most UnderWorlders are known to be more ruthless than, for example, the OverWorlders.
- Most underworlders resemble mythical creatures or "demons" as opposed to creatures and animals that exist on Planet Earth.