Kras was the Klingon representative sent to Capella IV to obtain permission for the Klingon Empire to mine topaline there in 2267. Kras supported Maab's revolt against the Teer Akaar in hopes that Maab would in turn award the Klingons the mining rights. Kras later betrayed Maab, and was killed by Maab's lieutenant, Keel, for his betrayal. (TOS: "Friday's Child")
Kras was played by Tige Andrews. His character was not named in dialog, but merely and impersonally referred to as "Klingon." However, the character's name was taken from the script and he was named in the ending credits.
Kras was the first Klingon character to be styled differently from Kor and the other Klingons in "Errand of Mercy". Kras' makeup involved no darkened skin or bushy, upswept eyebrows. This Caucasoid Klingon appearance was used again on Koloth, Korax and the other Klingons in "The Trouble with Tribbles" before reverting to the original makeup design in the episode "A Private Little War".