Trajok was a male humanoid wrestler in the 24th century, specializing in the Galeo-Manada style. Trajok's species had three sets of thorned ridges, two on each side of their foreheads and one in the middle.
In 2370, he coached Jadzia Dax in the technique while visiting Deep Space 9. When Arjin came to meet with her, Trajok answered Jadzia's door, initially taking Arjin off guard and making him think he had the wrong quarters. Trajok informed the initiate that she was in the shower, then asked if she was expecting him.
Afterward, he departed for Calondia IV, but promised Dax a rematch when he'd return the following week. (DS9: "Playing God")
Background information
Trajok was played by Chris Nelson Norris.
According to the script his name was pronounced TRAY-jahk, and he was described in the script notes as "a very alien man [...] with an athletic build."
The costume worn by Norris as Trajok was sold off on the It's A Wrap! sale and auction on eBay. [1]
Given Trajok's appearance, it would appear that he was actually a full-blooded Ktarian, as evidenced by the subtler features seen on the half-Ktarian Naomi Wildman of USS Voyager.