Parallel universe Kirk will kill you, and you'll never see him coming. In the episode "Mirror, Mirror" (1967), an ion storm adversely disrupted the transporter beam as Captain Kirk, Dr. McCoy (DeForest Kelly), Scotty (James Doohan) and Lt. Uhura (Nichelle Nichols) returned to the Enterprise after negotiating for dilithium crystals
with a benevolent race of beings. But a power surge sent the landing party to an alternate universe in which Starfleet had been replaced by a barbaric empire.
Aboard the I.S.S. Enterprise, Kirk discovered that his crew was one of treachery and bloodlust. Officers advanced through the ranks by assassination, and everyone was armed with phasers and daggers. To escape, Scotty duplicated the conditions of the storm by utilizing the engines to fuel the transporter. Luckily, Spock (Leonard Nimoy) of the bizarro universe was also a man of honor, as he helped Kirk and the others return to their world.
In one scene, audiences got a glimpse of the savage Kirk in the normal universe. The evil landing party had been found out by Spock and thrown into the brig. The unscrupulous Captain tried to buy off the Vulcan, but Mr. Spock simply found the whole exchange fascinating.