BetleH 'etlh

The betleH' etlh were a group of Klingons known as the Blades of the Bat'leth who were tasked to be infiltrators that would use surgery to disguise them as Humans for covert operations within Federation territory.

Known Blades of the Bat'leth

 * Kell

(TOS novel: Errand of Vengeance River of Blood)