Background: One of three Klingon Battlecruisers headed to Earth after the V’Ger Incident to share their data on the Cloud. When the lead ship’s commander saw the retrofitted Enterprise in action he wanted its secrets and ordered all three ships to pursue under cloak. They surrounded the Enterprise while still in Federation Space. Admiral Kirk refused to surrender threatening to use the new “Omegatron” device. Krell didn’t believe him and they pounded the Starfleet vessel relentlessly. Kirk hailed them again giving them a final warning, which they ignored. The Enterprise fired a massive burst through their phaser array that pierced the flagship’s shields and disabled them in one shot. Krell ordered them to retreat, taking his wounded pride and flagship in tow. (They were unaware that Kirk bluffed them, using a new design to channel warp power into the phaser banks that burned their emitter array and disabled their own warp drive.)
Appeared in Star Trek: Untold Voyages #1, Marvel Comics
Background: Ordered to the Needran system to relieve the qul HoH when the Enterprise arrived to investigate the attack on the Lafayette by alien forces in that sector and protect Klingon interests. When the qul HoH was attacked by those same aliens Khezri accepted Enterprise’s aid and many of the injured Klingons were treated in the Starfleet ship’s sickbay. Kirk and Khezri learned from difference sources that that the qul HoH’s sensors had been tampered with and the Commodore disseminated false information to Kedyn - qul HoH’s captain - about a joint convoy. Kedyn fell for the bait and Khezri too the Qapla under cloak to the ambush point. The 3 alien ships - now known as belonging to the Tyrion Legion - had poor cloaking devices and destroyed one of them before the other two retreated at high warp. Later assisted the Enterprise in meeting head on the 4 Tyrion Legion ships. They were cloaked to keep an element of surprise but Kirk managed to disable all four ships remotely, without any assistance from Khezri. Later that year they intercepted a Bird-of-Prey returning from neutral space. The Lur'Dech refused to stop and they fired a disabling shot on the Bird-of-Prey. Khezri learned of a plot to overthrow the legitimate Klingon Government and replace it with a faction more eager for war with the Federation. They travelled to Skellen III where Khezri revealed the information to Captain Kirk, as well as the fact that Admiral Tomlinson was a Klingon mole who now backed the renegade faction.
In 2290 Khezri took the Qapla to rendezvous with Okrona, there he made sure that Klaa understood that he wanted to find out why the Enterprise was so close to Klingon space, find out more about the Mardelvans and figure out what Kirk was after before he found it.
Background: Intercepted the Enterprise in orbit of Theta Leonis after Kirk, Spock and McCoy had beamed down for First Contact. The system was scheduled to fall in Klingon hands in 13 years and after filing to convince Scotty to take the Enterprise and depart the system Kalak led a landing party to the surface. Interference from the Enterprise prevented reinforcements from beaming down. After a confrontation against a supercomputer on the planet’s surface ended badly the Captain returned to the Arekkieh and prepared to attack the Enterprise out of spite. The supercomputer used a tractor beam on the surface to fling them out of the system at high warp.