Ultraman Zero

"Who are you?"

"Zero! Ultraman Zero! Son of Seven!

—Belial and Zero, Mega Monster Battle: Ultra Galaxy Legend The Movie

Ultraman Zero (ウルトラマンゼロ - Urutoraman Zero) is an Ultraman and the son of Ultra Seven. He was trained under Ultraman Leo after he was banished from the Land of Light by his father for attempting to take the Plasma Spark for himself. Zero relies more on physical strength and raw power in combat and is somewhat stubborn, however he has a caring side shown when he befriended a Pigmon while training and chose to save him rather than continue fighting. Ultraman Zero is considered one of the most skilled, among the most powerful Ultras in the Land of Light. As he is Ultraseven's son, he has a similar crest on his head like Ultraseven.

Ultra Galaxy Legend
In his debut appearance Ultraman Zero is training with Leo on the desert planet he was sent to, wearing the Techtor Gear Zero training armor. When Pigmon was in danger Zero decided to save him rather than continue his training battle with Leo. Leo and Ultraman King then reveal to him that saving the life of someone is the purpose of an Ultraman, and when he was exiled his father, Seven, was actually saving him from touching the Plasma Spark, otherwise he would have ended up like the evil Ultraman Belial who like Zero attempted to steal the Plasma Spark and ended up a threat to the entire Land of Light.

When Seven's Eye Slugger was sent as an S.O.S. King redeems Zero and frees him of his armour joining in the fight against Belial. When his father died in his arms Zero destroyed the remains of Belial's monster army and fought against Belial himself seemingly destroying him after a long battle.

But when Belial returned as Beryudora it took him with help from the remaining Ultra Brothers, Leo, Ultraman Astra, Ultraman Dyna, Rei, EX Gomora, and all of ZAP SPACY to destroy Belial. When the Plasma Spark was returned, Zero reunited with his revived father.

Ultraman Zero The Movie: The Revenge of Belial
In the film, Ultraman Zero The Movie, Zero is the main character fighting against three Darklops with his father and volunteers to go face the threat. On a distant planet, he comes across Ran and his brother Nao. With Ran dying and Zero running out of power, he takes Ran's body as a host. During his travels he becomes allies with several characters including Glenfire, Mirror Knight, and Jean-bot. Zero also battles against the army of the revived Belial now Galactic Emperor Kaiser Belial.

With the defeat of Belial, Zero left with Ran fully revived. A new alliance was formed with Zero calling it "Ultimate Force Zero".

Ultraman Saga
NOTE: This information is from an upcoming movie, as more details from the movie come out, more information will be added.

Zero will reappear in the upcoming movie Ultraman Saga, along Ultraman Dyna and Ultraman Cosmos and the Ultra Brothers. After defeating the remains of Belial's army, Ultraman Zero hears a voice coming from somewhere, after following the voice, he appears in another different universe, in another Earth, which is in reality Ultraman Dyna's universe. Upon arriving, Zero witnesses the heroic act of Taiga Nozomu, who sacrificed his life to save a child. Just like before, Zero was moved by his act, and decided to merge with him and make him his human host, but Taiga Nozomu is annoyed that he had to share his life with an Ultra and refuses to transform, due to a grudge against the ultras for the death of his parents during Alien Bat's first attack on earth. Very soon after, he meets with Musashi who arrived at the same time. Later he meets with the legendary hero Shin Asuka, and finds out he has been working with Team U since a long time.

Stats

 * Height: 49 meters
 * Weight: 35,000 tonnes (45,000 tonnes when wearing the Techtor Gear Zero)
 * Flying Speed: Mach 7
 * Home Planet: The Land of Light, Nebula M78

Powers/Abilities
Zero has demonstrated tremendous fighting skills destroying remains of an entire monster army and able to fight equally against Ultraman Belial, whereas all of his predecessors had difficulty against him eventually all losing. Ultraman and Ultraman Mebius have both stated that Zero has been thought to have limitless potential. He later gains more power from the Plasma Spark.
 * Ultra Zero Kick (ウルトラゼロキック, Urutora Zero Kikku): A flying kick similar to Ultraman Leo's Leo Kick.
 * Leo Zero Kick (レオゼロキック, Reo Zero Kikku) A Flying kick with Ultraman Leo.
 * Emerium Slash (エメリウムスラッシュ, Emeriumu Surasshu): A beam similar to Ultra Seven's Emerium Beam.
 * Wide Zero Shot (ワイドゼロショット, Waido Zero Shotto): A "L" style beam similar to Ultra Seven's Wide Shot.
 * Zero Sluggers (ゼロスラッガー, Zero Suraggā): Two throwing weapons on his head that are similar to Ultra Seven's Eye Slugger.
 * Zero Slugger Attack (ゼロスラッガーアタック, Zero Suraggā Atakku): A slashing attack with the Zero Sluggers.
 * Zero Twin Shoot (ゼロツインシュート, Zero Tsuin Shūto): A powerful beam from his chest with the Zero Sluggers.
 * Zero Twin Sword (ゼロツインソード, Zero Tsuin Sōdo): The Zero Sluggers which turned into a crescent-shaped blade using the Plasma Spark's energy.
 * Plasma Spark Slash (プラズマスパークスラッシュ, Purazuma Supāku Surasshu): A slashing attack with the Zero Twin Sword.
 * Leo-Zero Double Flasher: A combination attack with Ultraman Leo where the the Ultras combine their energies into a powerful beam attack.
 * Combination Zero: A combination attack with Ultraseven using both the Eye Slugger and the Zero Sluggers. The bladed projectiles circle around each then cut apart an enemy.
 * Ultra Zero Lance: Summoning an Ultra Spark from an Ultra Brace, Zero throws it through an enemy and continues until it returns to Zero.
 * Size Change: Like his father, Zero can change his size from human size to his proper giant height. He uses the same stance as his father, crossing arms and bringing upright to the sides of his head to grow and the reverse to shrink

Ultimate Zero
In Ultraman Zero The Movie: The Revenge of Belial, Zero gains the Shield of Baradhi from Ultraman Noa, which becomes the Ultimate Aegis which in turn has Zero become Ultimate Zero. This form gives Zero chest armor and a sword on his right arm in addition to more power. This form was first used to fight Ultimate Galactic Emperor Kaiser Belial.

Trivia
In Ultraman Saga movie, Ultraman Zero's rise is a combined sound between the Leo ring and Ultra Eye.