I'll enter. After seeing many other entries, I most likely won't win.
Lord Bolite
On Mata Nui, after a horrible chemical accident, a Matoran named Bolite was mutated into a crab-shaped creature. When he returned home, his best friend, Moran, stared at him in fear. Moran took out his spear. Bolite shivered, and refused to fight. But Moran began to attack. Defending himself, Bolite blocked the blows, instead of fighting, as Bolite is a pacifist. Rage, and tears filled his eyes until Bolite became filled with rage and grabbed Moran's neck. He choked Moran until he became unconscious. Bolite crushed Moran alive, nearly killing him. Bolite was still filled with rage. and swore revenge on every Matoran because every Matoran he knew betrayed him, and were most likely killed by Bolite. It has been 20 years, and now he is Lord Bolite, a homicidal maniac who murders anybody who looks at him in fear. After his 2,000th murder, he began to dwell in a hole, where he would grab and kill anybody who walks by.