Grimlock

He was the culprit of his in-game and real-life wife, Griselda’s death. He killed her because he didn’t like the changes in her personality. At first he didn’t want to aid Caynz and Yolko in their plans to catch Griselda’s killer by forging them weapons to use in the in-AREA murders. Evenutally he did, but not with good intentions. He helped so he could have Caynz, Yolko and Scmitt together and get them killed with the help of the Laughing Coffin. But the plan failed, because Kirito came to the rescue. He is caught by Asuna. It is unknown to what happened to him in the remaining time of SAO, but in the end, he was logged out.