Origin

Byth was the greatest thief on the planet Thanagar, a world where people steal not for profit, but simply for the thrill of it. After bursting into the laboratory of one professor Krotan, Byth stole and swallowed the only existing sample of Krotan's greatest discovery: a pill that allowed the human mind to control the molecular configuration of the body. This pill gave Byth the power to alter his shape to that of any living creature, bird or beast.

As administrator he replaced Paran Kathar as leader. He exposed a revolutionary conspiracy seemingly led by Katar Hol's father. Byth demonstrated the strength of the body of Thanagar when the mind goes wrong.

Having achieved the ultimate thrill on Thanagar, Byth stole one of the planet's newly developed star cruisers, and fled to Earth in search of bigger and better thrills. He was pursued by Thanagarian Police Officers Katar and Shayera Hol (Hawkman and Hawkgirl) who ultimately crash land on Earth. As for Byth, he had eluded his pursuers and believed the Hols to be dead until centuries later.

Even though they had split up, both Carter Hall and Kendra Saunders reunite because they have the same problem. They are both having trouble with their inner hawk avatars, with Katar and Shayera Hol want to take control of their human hosts. Kendra decides the only way they can be free of their past lives is by exorcising their hawk avatars but Carter disagrees and believes there must be another way. Kendra gets in contact with Buddy Baker aka Animal Man because his dealings with animal spirits have worked in the past thanks to Vixen’s tutelage.

Before Buddy began the ritual, Carter shows up to apologize to Kendra and agrees to the exorcism. However, Buddy soon realizes from his animal instincts that Carter is actually Byth Rok. Byth was hoping for Baker to exorcise Kendra’s avatar because this would mean the removal of her powers and the memories of her past lives which included Byth’s existence. Byth battles Kendra and knocks out Buddy then he makes his escape with Kendra.

With Kendra as his hostage, Byth can draw out the actual Carter Hall since Kendra and Carter share a psychic link between one another. Buddy regains consciousness and uses his animal tracking skills to locate Kendra’s location. Buddy is soon joined by Hawkman and they both find Byth’s secret hideout. Byth is apprehended and taken back to Thanagar for his crimes.

New 52

Justice League of America

In Justice League of America #1, Hawkman is seen executing a man who he is claiming to be the criminal "Byth Rok" although the man pleads and insists that he isn't Byth.

Justice League United

Soon after it is revealed Byth is in the Polaris system working with Lobo.

He hire Lobo to capture various alien races through the cosmos for scientist of Project Ultra could combine their DNA to create a perfect being and most powerful creature in the Universe: Ultra, the Multi-Alien.

Not long after it is revealed that he was the leader of a religious cult that aims to bring Infinitus a powerful entity from 31 century using Ultra as vessel,so that it consumed the whole universe within himself

Powers & Abilities

Pre-Flashpoint

New 52

• Superhuman Strength

• Durability: He is able to take blows from a enraged Supergirl and Martian Manhunter.

• Shape-Shifting: Despite being a thanagarian Byth possess shape-shifting capabilities similar to Plastic Man or even Martian Manhunter,being able to assume shapes of anything existing or imagined and even grown extra limbs,increase size and control its malleability.

• Malleability (Elasticity/Plasticity): He can stretch his limbs and body to superhuman lengths and sizes. There is no known limit to how far he can stretch his body.

• Regeneration: Byth can recover from almost any injury,even when is severed into several pieces.

• Immortality/Longevity: During a conversation with Supergirl, he implied to be older than she could ever imagine.

• Telepathy: Byth shown some telepathic abilities, but not powerful as Martian Manhunter. He was able cast J'onn out of Ultra's mind; but Byth was very close to Ultra, and J'onn was thousands of miles away (so far away in fact that he needed help from saturn girl to contact Ultra).
• Flight: He's able to use his shape-shifting abilties to create wings.
• Claws

Abilities

Besides his shape-shfting Byth is intellectual genius and incredible tactician.

He is a gifted biologist/geneticist able to create beings like Ultra, which was created from the cells of various beings and the universe races.