In 'The Hunted,' James Cromwell plays Prime Minister Nayrok of the planet Angosia III. The Enterprise has made its way to the planet to consider its involvement in the Federation, but before they can get to it, Nayrok asks them to hunt down a dangerous escaped criminal. Captain Jean-Luc Picard (Patrick Stewart) and his crew learn that this prisoner is a genetically modified soldier that the government has deemed too dangerous for traditional society. Captain Picard does not take kindly to Nayrok's abandonment of his soldiers, and when an insurgency arises, Picard refuses to help Nayrok stop it.
In the two-part episode 'Birthright,' Worf (Michael Dorn) learns that his father might not have perished in combat. Yridian information broker Jaglom Shrek (Cromwell again, but, this time beneath layers of alien makeup) claims that Worf's father is alive at a Romulan prison camp. Even though he doesn't initially believe Shrek's intel, Worf makes his way to the Romulan camp to see for himself.
Cromwell, a prolific character actor, went back to the Trek well a couple more times, playing Minister Hanok on the Deep Space 9 episode 'Starship Down' and prickly warp-technology pioneer Zefram Cochrane in the feature film Star Trek: First Contact.