Conan O'Brien was a late 20th/early 21st century comedian who had a television show which aired late at night in the early 2000s United States.
In Detroit in October 2004, Loomis asked Lawrence Strode to come back to the blood bank to fill out some records, but Strode was apprehensive, citing that it was already 11:00 pm, and he was concerned that he might miss Conan. (ENT: "Carpenter Street")
Star Trek: Lower Decks guest star Andy Richter frequently appeared as O’Brien’s sidekick on the program Loomis mentioned.