Hector Ruiz

Hector "El Camaleón" Ruiz was a ex-military soldier and notorious assassin, who was responsible for at least 41 murders, including the murder of a police captain in Mexico. He appeared as the primary antagonist of the Season 2 episode Kame'e.

Hawaii 5-0
Ruiz was hired by a Mexican drug cartel to kill members of SEAL Team 9 who had previously launched a raid on the cartel in question, resulting in the death of the cartel's leader while his brother swore revenge.

Ruiz killed Petty Officer Clay Garcia by shooting him in the head and the other SEAL with a car accident. Both deaths were originally thought to be accidents but upon closer inspection, Max Bergman confirmed that the deaths were actually murderer.

Ruiz attempted to kill Lieutenant Bradley Jacks by poisoning him and throwing him out of a plane but luckily, Lieutenant Commander Steve McGarrett came to the rescue, saving Jacks's life while Ruiz later returned, believing that Jacks was dead, only to be confronted by Detective Danny Williams and Lieutenant Chin Ho Kelly who attempted to arrest him but Ruiz drew a gun, forcing Danny and Chin to shoot Ruiz dead in self-defense.