(written from a Production point of view)
King Abdullah II bin al-Hussein (Arabic: عبدالله الثاني بن الحسين) (born 30 January 1962; age 59) is the king of the Hashemite Kingdom of Jordan. An acknowledged fan of Star Trek, King Abdullah (then a prince) appeared as an uncredited extra in the Star Trek: Voyager second season episode "Investigations". Voyager executive producer Jeri Taylor commented, "Take away the title and the trappings, and at the core you have a Star Trek fan." (Star Trek Monthly issue 16)
Abdullah's cameo was arranged as a surprise for him by his US advisor. The prince – who, at the time of his cameo, was thirty-four years old – enthused, "I would have been thrilled just to visit the set but this is too much." After being put into makeup, given pointed sideburns and then fitted for his uniform (a lieutenant of the sciences division), he rehearsed and shot his scene. (TV Guide, 17-23 Feb., p. 26) He appears in the episode's opening scene as a science officer who speaks with Harry Kim as the scene fades in. He was not given any spoken lines, however, because he was not a member of the Screen Actors Guild (now SAG-AFTRA). After filming his cameo, he was crowded by well-wishers, including Robert Picardo, who secretly presented the delighted guest with an autographed picture of himself in his role of The Doctor. (TV Guide, 17-23 Feb., p. 26) Abdullah subsequently gave a party for the Voyager cast. (Star Trek Monthly issue 16) During his time on the Star Trek: Voyager set, Abdullah also invited Robert Picardo and Neelix actor Ethan Phillips to his own country of Jordan, an offer that Phillips took up during the hiatus between Voyager's second and third seasons. (Star Trek Monthly issue 20) Picardo also apparently took up the offer, where upon their arrival, Abdullah "arranged tours of the country's historical monuments, he had also laid on a mini-convention of the programme's fans." 
Abdullah was crowned King of Jordan in 1999.