Admiral Klug was a Klingon Starfleet officer from the 27th century. (Star Trek: Mirror Wars)

Not much is known about Klug. He seemed to be always at odds with President Zut and was quick to react to Aaron J. Riker's message warning of the mirror universe attack on September 11, 2602.

About a month later, he proposed a plan to the Starfleet admirals to attack the mirror Earth.

Klug became the Starfleet lead admiral in January 2599. ("Her Flags Unfurled")