After the end of "Deep Space Nine", O'Reilly made one further appearance in "Star Trek" as the character Kago-Darr in the "" episode "". He was thankful for the role, as he felt that the writers and producers of the show had created it for him specifically as his family was trying to adapt following the birth of his triplets. After his retirement from acting, he continues to attend "Star Trek" conventions, including performing in character as Gowron alongside J. G. Hertzler as fellow Klingon Martok. In 2020, he reprised the voice of Gowron and the Klingon Aakar, an ancestor of Gowron's, in the video game Star Trek Online.