K'Tal was a high-ranking member of the Klingon High Council.
When Captain Picard needed a cloaked ship to get to Romulus in 2368, Picard asked Worf to contact anyone on the Council he could, and suggested K'Tal specifically. K'Tal did not respond, but junior adjutant B'iJik did to state that Gowron was unable to talk to Picard. (TNG: "Unification I")
K'Tal was played by late actor Ben Slack in his appearances in "Redemption" and "Redemption II".
According to K'Tal's back story found in the script for "Redemption": "K'Tal is an older member of the Council. He follows neither Gowron nor the [Duras] sisters. He serves the Empire. A man who has been on the Council longer than anyone else and will probably still be here when the others are all gone."
K'Tal makes an appearance in the non-canon novel The Art of the Impossible. He is also mentioned in the Star Trek: Klingon Empire (formerly I.K.S. Gorkon) series; both Captain Kargan (who appeared in "A Matter Of Honor") and his father, General Talak, belong to K'Tal's House, but are described as not sharing his sense of honor.