A member of House Jhereg, and an assassin.
Ishtvan was hired by Kragar to kill a Left Hand sorceress after Vladimir Taltos heard she was involved in rumours about the Jhereg Treasury missing money. The job was in the interest of preventing the rumours long enough for Vladimir to assasinate the person who stole the operating funds to deliver the Jhereg response. Vladimir was impressed with how quickly Ishtvan disposed of her, and told Kragar to keep him in mind for the future.
In the future, Vladimir hired him to shadow and attempt to put down Quaysh who was sent by Herth to assasinate him during a Jhereg war between the two. Ishtvan planted a short iron pike into his target's back in the middle of his second assasination attempt. Vladimir was not able to identify where Ishtvan made his move from and withdrew.
After Vladimir insulted the Jhereg Imperial Representative and offered evidence to the Empire against a Jhereg Council member, Ishtvan was hired to assasinate him. He located him in Smallcliff, and worked with the Baron Smallcliff to kill him. They were not able to cooperate positively together, likely due to Baron Smallcliff's attempt to kill Vladimir by sending seven of his bladesmen, which alerted him to his situation despite inflicting a significant amount of damage on him.
Vladimir used their relationship to inspire his distrust in a direct confrontation with the two. Ishtvan then turned his back on him in a moment of carelessness in order to attempt to attack Loiosh and Rocza with a Morganti dagger. Vladimir's sword took him in his back, directly above the heart.