Reaper


 * Psychotic: Reaper is an infamous international mercenary with a massive body count. Rather than for money, it's obvious he's pursued this career choice just to kill, despite his aloof and cool exterior. However, this stoicism is shattered when he uses his ultimate, where he roars "DIE! DIE!" DIE!" like a lunatic as he animalistically shoots up the area around him.
 * Sociopathic: Reaper fully admits this with the voiceline "I'm not a psychopath. I'm a high-functioning psychopath." His needless body count, lust for murder, and unbiased antisocial narcissism further proves this.
 * Spiteful/Haughty: When he's not murdering people, Reaper is still an incredibly mean-spirited and vindictive person, extremely insulting and condescending to his allies when out of battle and to his enemies when in battle, even being as petty as to make fun of McCree's attire. This trait actually leads to his defeat twice, as twice he had Winston pinned and ready to execute, before going out of his way to insult and belittle him one last time, allowing Winston to get a second-wind and defeat him. The first time, it was to stomp on Winston's glasses, the second time, it was to call Winston a racist, bitter nickname.
 * Xenophobic: Like Junkrat and Torbjörn, Reaper has absolutely no respect for omnics, declaring "Tin cans, a dime a dozen." when killing Bastion or Zenyatta.