| Mr. J'Dan. | |
| Name: | J'Dan |
| Gender: | Male |
| Species: | Klingon |
| Actor: | Henry Woronicz |
J'Dan was a Klingon scientist that served in the Officer Exchange Program in the late 24th century.
In 2367, J'Dan was assigned to the Federation starship Enterprise. Being as he suffered from Ba'ltmasor syndrome, he had to stop at sickbay to get regular treatments. While doing this, he sometimes chatted with the medical personnel, including Doctor Crusher, but the medical technician assigned to him was Crewman Simon Tarses.
Shortly after arriving on the Enterprise however, the Dilithium articulation frame in the warp core exploded. It was suspected that it was sabotage, and a Starfleet arbitrator was sent in to investigate. Rear Admiral Norah Satie found that he had been using a Klingon hypospray, which he used to treat his condition, as an optical chip reader, with which he sent schematics for the Dilithium chamber to the Romulans. He was later found innocent of blowing up the Dilithium articulation frame, but sent to Qo'noS for trial for spying on the Federation for the Romulans. (TNG: "The Drumhead")