Tryla Scott was a human female introduced in the Star Trek: The Next Generation episode Conspiracy.
She was portrayed by Ursaline Bryant.
Along with fellow Captains Walker Keel and Rixx, Scott became aware of a number of strange patterns of behavior at Starfleet. Her suspiscions turned in to alarm as a number of prominent people died - including McKinney, Ryan Sipe, and Onna Karapleedeez - in what Starfleet termed a series of accidents.
Keel was able to convince his old friend and USS Enterprise Captain Jean-Luc Picard to meet him, Rixx, and Scott on Dytallix B. There the three of them convinced themselves that Picard had not been co-opted. Scott and the others warned Picard of what they were seeing. Initially unconvinced, when Keel died a short time later Picard began to realize something was very wrong in the Federation.
Unfortunately, Scott herself was infected after the clandestine meeting by one of the Neural Parasites that was behind the conspiracy against the Federation. Once under parasite control the parasite was able to warn its brethren that Picard was on to them.
Under parasite control Scott returned to Earth and sat in on the dinner her fellow parasite infected officers held for Captain Picard. When William Riker arrived to rescue Picard she attacked both Riker and Picard, but Riker shot her with a phaser set to kill. The parasite then left Scott's body. The infestation ended a short time later when Picard and Riker destroyed the Parasite Spawnmother leading the conspiracy.
It was later discovered that the orders naming Scott the Captain of the USS Renegade had no traceable authorization codes. Picard theorized that the Preservers had acted to put her in a position where they needed her to be, but she died before her potential could be fulfilled.