Deathmatch

A deathmatch is a game where the players attempt to kill each other.

The term has been used twice in Yu-Gi-Oh! series, although only once did a player die.

Katsuya Jonouchi vs. Chopman
One of the stages of Death-T, involved battling the serial killer, Chopman, in a fight to the death, inside the Murderer's Mansion.

Yugi, Jonouchi, Anzu and Honda were forced to send one of their players into a chamber with the Chopman or Kaiba would order the Chopman to kill Johji.

Jonouchi stepped forward as their player. He had himself handcuffed to a chain, which strung through a podium in the center of the room and had the other end cuffed to the Chopman. The two players were to choose from an array of weapons, which hung from the ceiling, including a scythe, a flail, a machete, a chainsaw and an axe. To get them, they had to stand on the podium in the center of the room.

The Chopman choose the chainsaw as his weapon and was able to pull Jonouchi over to him, by yanking the chain. Fortunately for Jonouchi, the chainsaw got stuck in the podium.

Knowing he couldn't stand-up to the Chopman's brute force, Jonouchi used a candlestick to unpick his end of the handcuff, while the Chopman tried to free the chainsaw. Jonouchi then attached the chain to the door and slipped the candle inside the cuff. Once the Chopman freed the Chainsaw, he yanked the chain, thinking he would pull Jonouchi, but instead ripped the door out of the wall. The candle then hit the oil-covered floor, setting the Chopman alight, while Jonouchi escaped.

Yusei Fudo vs. Mr. Armstrong
Yusei Fudo faced Mr. Armstrong in a Duel, where both players received massive shocks when they took damage. Although neither player was killed. The Japanese title for Yu-Gi-Oh! 5D's episode 9 referred to it as a Lightning Deathmatch.

Yusei stood up to Armstrong, after Armstrong belittled the inmates at The Facility and framed Bolt Tanner. Armstrong proposed a Duel, where if Yusei wins he will forget Bolt Tanner's crime and won't lengthen Yusei's sentence. Yusei said that he will put himself at Armstrong's mercy for the rest of his life, should Armstrong win. Yusei agrees to face Armstrong at a time, which interfered with his escape plan with Alex.

Using cards given to him by the other inmates, Yusei formed a Deck. He faced Armstrong in a arena, where both players were chained to spot and got shocked if they took damage. However, Armstrong rigged the arena, so that he couldn't get shocks. Armstrong also used security cameras to see the cards in Yusei's hand. Alex also abandoned his escape plan and broke into the control room, where he switched on Armstrong's shocks and brook the computers, so the settings couldn't be altered.

Yusei's Life Points were lowered to 100 and he almost ran out of cards. However, using the last card in his Deck, "Rubble King" in combination with "Blasting the Ruins", he turned the Duel around and defeated Armstrong.