Deadly Six

The Deadly Six (六­鬼衆) are the primary antagonists in Sonic Lost World. They are a villainous gang of six menacing Zeti. Originally formed several years ago, Dr. Eggman discovered the Deadly Six and tried to harness the power of the group in an attempt to defeat Sonic the Hedgehog and conquer the world. However, due to Sonic's recklessness, the Deadly Six broke free and threaten to destroy the world on their own, forcing Sonic and Eggman to team to stop them. In the end, the Deadly Six were defeated by Sonic and their plans were foiled.

Concept and creation
According to Takashi Iizuka, the Deadly Six were meant to bring a “sense of danger and humor” to the story of Sonic Lost World. According to another interview with Takashi Iizuka at Summer of Sonic 2013, the Deadly Six are based off of "oni", which is a Japanese demon. The main motif is that the Deadly Six were based off of an  "ogre", a mythological creature.

Past
The Deadly Six were formed several years prior by Master Zik. However, it was Zik's student Zavok who would assume leadership over the group as his demeanor and intelligence made him well-suited for the position. It is unknown what activities the group has been involved in the years that followed.

Sonic Lost World
In the present day, shortly before the events of Sonic Lost World the Deadly Six were enslaved by Eggman using a Cacophonic Conch, which Eggman used to cause them pain if they disobey or offend him. Zazz, always eager for a fight, volunteered to fight Sonic first but was defeated twice. Eggman sent Zomom after Sonic next, but Sonic defeated him twice. During a confrontation between the Deadly Six and Eggman, Sonic appeared and recklessly knocked the Cacophonic Conch away. Now free from Eggman's control, the Deadly Six rebelled against him, commanding all of the Badniks they took control of to attack everyone present. Despite this, Sonic, along with Tails, Eggman and his two robot henchmen Orbot and Cubot escaped safely from the danger.

Master Zik was the third to fight Sonic. The Deadly Six then used Eggman's unstable Extractor to absorb the Earth's energy, growing stronger over time. Zeena fought Sonic fourth. Later on, the Deadly Six decided to capture Sonic and turn him into a robot under their control, but they captured Tails instead. Zor fought Sonic fifth and Zavok fought him last.

After each of the Deadly Six had been defeated twice by Sonic, Zavok proceeded to transform Tails into a robot as an act of revenge. Zazz, Zomom, and Master Zik attacked Sonic and Eggman on Lava Mountain, seemingly killing Eggman, Orbot and Cubot as they fell towards the bottomless pit while Sonic survived. Sonic defeated Zazz, Zomom and Master Zik in Zone 1. Eventually the hedgehog confronted the remaining of the Deadly Six, Zeena, Zor and Zavok and tried to force Sonic to surrender by sending in the roboticized Tails and ordered him to attack Sonic. Tails, however, shot at the Zeti, causing them to flee as Sonic pursued them at Zone 3. One by one Sonic defeated Zeena, Zor, and Zavok.

The fate of the Deadly Six is left unclear, as each of them disappeared after their defeat (in the Wii U/PC version of the game, Zazz, Zomom, Master Zik and Zeena disappear in a puff of smoke, while Zor and Zavok perish in lava). However, Eggman vowed to try and control the Deadly Six again after his defeat, which would suggest that they somehow survived, and merely escaped (which they did in the Nintendo 3DS version instead of seemingly dying).

Sonic Dash
In Sonic Dash, Zazz was featured as one of the two bosses fought randomly while in a run. All members of the Deadly Six appeared as cameos in the game's downloadable wallpapers of Sonic Lost World.

Super Smash Bros. for Wii U
In Super Smash Bros. for Wii U, the Deadly Six makes a cameo appearance as one of the collectible trophies representing the Sonic the Hedgehog series.

Sonic Runners
In Sonic Runners, during the "Zazz Raid" event, the Deadly Six made their reappearance. This time around, Zazz returned to get his revenge on Sonic by using Power Rings to boost his powers. Each time he confronted Team Sonic however, he was defeated. Between Zazz's battles, the Zeti would go to each of the other Deadly Six for advice on how to beat the heroes, though their advice either did not work or the others just tease him. Zavok told him to keep on fighting, knowing full well that Zazz could not hope to beat Sonic; however, Zazz's constant failures allowed the Zeti to gather the information they needed so that one day, they would be able to destroy Sonic.

Archie Comics
In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, the Deadly Six were enslaved by Dr. Eggman with the Cacophonic Conch, but got liberated by Sigma, a villainous robot from an alternate world. The group briefly teamed up with Sigma to aid with his plans, only to betray him when they received power-enhancing armor from him. However, Sigma took control over the Deadly Six using their armor and instated them as his new commanders. They were eventually freed by the Unified Army, and their involvement with Sigma would be erased from history by Xander Payne.

At some point in the not-so-distant future, the Deadly Six would be enslaved by Dr. Eggman once more.

Trivia

 * Despite being called the "Deadly Six", they are only called in that way once by Eggman in Sonic Lost World, as in the rest of the game they were referred to as "Zeti" by the characters.
 * Similar to other powerful entities, Eggman attempts to control the Deadly Six in order to take over the world, only for them to turn against him. The main difference is that it happens early in the game, rather than towards the end.
 * Interestingly, the Deadly Six are portrayed in a more colorful, vibrant fashion than typical Sonic villains, but their dialogue and behavior are much darker, even going as far as to directly reference death, mind control and even genocide. The game's E10+ rating is mostly due to these characters' behavior, according to the ESRB website.
 * Zavok and Zeena are the only Deadly Six members whose names are not mentioned in Sonic Lost World.
 * While the Deadly Six seemingly vanished after their final battles in the Wii U version, in the Nintendo 3DS version they survive and merely fly away like in previous battles.