to defeat a common enemy. It also marked the passing of the film franchise from the original series cast to that of The Next Generation. Characters more prominent on subsequent series A few occasional recurring characters introduced in one series continued into other series, sometimes attaining more significant roles in their subsequent Trek series than in the one in which they were first introduced: Spock's father Sarek appeared in only one episode of the original series, but became a more developed character in three movies and appeared in the Next Generation episode named after him and the first part of "Unification". Sarek's appearance in the former is described in The Star Trek: The Next Generation Companion as "the first major unifying event tying together the old and new Trek eras since McCoy's cameo" in the original series. Sarek later appeared in Star Trek: Discovery. Recurring character Q, originally introduced in the premiere episode of Next Generation, continued to appear in episodes of Deep Space Nine, Voyager, Lower Decks and Picard. Teleplay writer Robert Wolfe found it difficult to incorporate Q into the DS9 universe as the character had been conceived so much as a foil for Captain Picard. He eventually decided to use Q to show personality differences between Picard and Sisko. It was also difficult to decide how to introduce Q into Voyager, as it was necessary to explain why Q did not return the ship to Federation territory. Although appearing in only five episodes of The Next Generation and six episodes of Voyager, the character of Reginald Barclay became quite pivotal to the story-arc of the final season of Voyager, significantly contributing to the reestablishment of contact between the ship Voyager and the Federation. Barclay also appears in a cameo role in the eighth movie in the film series, Star Trek: First Contact. Three Klingon characters from separate individual episodes of the original series, Kor, Koloth and Kang, all appear in the Deep Space Nine episode "Blood Oath", and Kor further appeared in DS9 episodes "The Sword of Kahless" and "Once More Unto the Breach". Crew members who worked on "Blood Oath" felt that a "special connection" was being made to the original series. Kang made an additional cameo appearance on Voyager, verbally dueling with Captain Sulu in a brief scene of the episode "Flashback". The two Ferengi, Arridor and Kol, were minor characters in the TNG episode