He sat the entrance exam on Relva VII in 2364, and he narrowly beat out Wesley Crusher for a place. He had trouble with the dynamic relationships part of the exam, but with the help of Crusher managed to score the second best time ever for the test. He regarded this as being unfair to Crusher, but was assured that Crusher's help was not the deciding factor between them. Apart from being the first Benzite in Starfleet, he was also famous for designing the Mordock Strategy. (TNG: "Coming of Age")
Mordock was from the same geostructure as Mendon and they therefore looked alike. Wesley Crusher commented on the similairty when Mendon came aboard the USS Enterprise-D in 2365. (TNG: "A Matter Of Honor")
Mordock was played by John Putch in his first of three Star Trek appearances. Putch became the first Star Trek: The Next Generation guest star to play two separate characters from the same species, also playing Mendon in "A Matter of Honor."
The script for "Coming of Age" describes Mordock as "a powerfully built alien with a special suit using circulating gas tubes." 
Of playing Mordock, Putch recalled; ""I was always a Star Trek fan. When I got to work on the show it was really fun. I was an alien-of-the-week. Big make-up deal. Michael Westmore made a giant head for me and it was fun. I became a trading card and an action figure." Of going on to play another Benzite, he commented; "I was all very impressed by that. I thought, 'Ah, they love me, they love me.' What they really loved was that it was me, because they'd spent all that money on making that blue head and it was form fitted to me … I don't fault them for that. I would have done the same thing, but it's funny how you are naive about these things when you're just an actor." 
Mordock was the first Benzite to appear on-screen. All the makeup department had to go on when designing him was a brief description in an early draft of the script for "Coming of Age." They created one major appliance that covered most of actor John Putch's head and additional pieces that covered his upper lip, chin and eyelids, both of which were an unusual configuration of "puffy eyes" with lids that "folded back on themselves like Venetian blinds." The mouth area and earlobes possessed a set of catfish "feelers" while the overall headpiece was painted blue with oranges and yellows worked in to make the skin color look more lifelike. (Star Trek: Aliens & Artifacts, p. 110)
In 1993, Playmates Toys released a "Mordock the Benzite" action figure complete with type 2 phaser, tricorder with holster, scanner and monitor. The description on the packaging reads; "Sincere. Eager. Polite. Efficient. These social traits seem to be the bases for all geo-structures on Benzar. Mordock is well-known throughout the galaxy for his strategic planning - in particular, the Mordock Strategy, which he developed prior to joining Starfleet. He is the first Benzite to attend Starfleet Academy, and he scored in the top 1% on the entrance exams. Mordock maintains a lasting friendship with Wesley Crusher of the U.S.S. Enterprise.'"