A large Klingon command ship used by the Klingon Empire during the Dominion War.
The Negh'Var class is a large Klingon warship of the late twenty-fourth century, far bigger than the Bird-of-Prey and used as a command vessel and flagship. The design first appeared in the possible future shown in The Next Generation finale, All Good Things.
In Deep Space Nine, Chancellor Gowron used a Negh'Var as his flagship when the Klingons invaded Cardassian space in 2372, convinced that the new civilian government had been infiltrated by changelings. Worf refused to support the invasion, and Gowron brought his forces against Deep Space Nine before agreeing to withdraw.
The invasion caused the Klingons to withdraw from the Khitomer Accords for a time. Once the Dominion threat became clear, the Empire returned to its alliance with the Federation, and Negh'Var-class ships fought in the Dominion War alongside Birds-of-Prey and Vor'cha-class cruisers.