Kul'Tiras Marines

The Kul'Tiras Marines were Kul Tiran humans following Daelin Proudmoore. When the admiral learned about the new Horde stealing ships from Southshore, he and his navy quickly tracked the orcs to the open seas, but both fleets were then hit by a storm that caused some of their ships to land on the Darkspear Islands.

The Marines were later seen hunting the Island Trolls. After Sen'Jin met Thrall, Thrall in turn helped the trolls face the humans and destroy their base. The rest of the Kul Tiran were captured by the Underworld Minions.

Speculation
Members of the Marines stationed in Theramore could possibly be survivors from the Darkspear islands, or they could have come directly from Kul Tiras, either during the Third War with Jaina Proudmoore or at any point following the establishment of Theramore. It is also worth noting that Jaina took Kul Tiran ships in order to travel to Kalimdor, and Cycle of Hatred also mentions several characters coming from Kul Tiras to Kalimdor, such as Lorena, who could have possibly been a part of the Marines.