Which Ukrainian mob boss appears in Dexter season 7?

Isaak Sirko is the Ukrainian mob boss who appears in Dexter season 7.

Played by Ray Stevenson, Isaak is a senior figure in the Koshka Brotherhood, a Ukrainian crime syndicate operating in Miami. He arrives after the disappearance and death of Viktor Baskov, one of his associates and his lover, and initially hunts Dexter to avenge Viktor.

Isaak begins as a major antagonist, but his relationship with Dexter becomes more complicated. After conflict with the Brotherhood leaves him vulnerable, he asks Dexter for help against former associates and assassins. Their shared isolation and personal losses create an uneasy respect between them.

The other names in the choices are connected to the same storyline but are not the mob boss: Viktor Baskov is Isaak’s subordinate and lover, Jurg Yeliashkevych is his bodyguard, and George Novikov manages a Brotherhood-linked club. Isaak is also nicknamed “Volk,” meaning “Wolf” in Ukrainian.