Takaido

Zygor is one of Bandit Keith's three henchman in Yu-Gi-Oh!

The Anime
Sid is the cool guy of the trio, with long red hair and an Australian accent.

Duelist Kingdom
Sid, Bonz, and Zygor attacked Joey Wheeler and took him to a cave where Bonz dueled Joey. After Yugi, Téa, Tristan, and Bakura appeared to cheer Joey on, Tristan attacked Sid and Zygor, but Sid threw a rock at him, and Zygor punched him. After Joey defeated Bonz, Keith had Bonz, Sid, and Zygor seal the exit with a boulder to prevent Yugi and the others from escaping. Afterward, Keith beat the three of them up and took their star chips.

Battle City
Sid entered Kaiba's tournament in Battle City alongside Bonz and Zygor. Rather than duel for star chips, they put on zombie masks and scared people at the cemetery to get their locator cards. They attempted to do this to Yami Bakura, but he was unaffected by it, and dueled Bonz, taking the duel to the Shadow Realm. Yami Bakura gained the advantage, and soon told them that they were in the Shadow Realm, and if Bonz lost, they would be trapped there forever (or at least until Yami Bakura chose to set them free). Sid tried to run, but came back from the other side, as one cannot run from the Shadow Realm. Yami Bakura defeated Bonz, so he, Sid, and Zygor became trapped in the Shadow Realm, vanishing into shadowy clouds in the ground. Yami Bakura then took their locator cards so he could enter the final rounds.

He has not been seen since. In the Japanese version, they were sent to Hell rather than the Shadow Realm (though there is little difference between the two), with hands pulling them into the ground.