Klingon Bird-of-Prey
Name: IKS Marcus
Affiliation: Terran rebellion
Type: warship
Class: Klingon Bird-of-Prey
Status: destroyed in battle, 2372

The IKS Marcus was a Klingon Bird-of-Prey commanded by Kruge. He used the ship, named after David Marcus, to help the Terran rebellion in its battle against the Klingon-Cardassian Alliance. He hoped that if he could fight a battle in Marcus' name it would help Marcus get into Sto-vo-kor. ("A Debt of Honor")

It was most likely the mirror universe equivalent of a D-12 or B'rel-class ship.