The phrase "titular detective" refers to the main or central detective character in a story, usually the one mentioned in the title or the one who is the focus of the narrative. Full definition
Add in a compelling if simple story and the always entertaining titular detective, and you get a great adventure for fans of the franchise. (thatvideogameblog.com)
The star of the show is of course the titular detective, a gruff, sarcastic English - speaking Pikachu who doubles as both the player character's sidekick and a key piece in the narrative's over-arching mystery. (vg247.com)
According to Deadline, Wood will play Gently's assistant Todd, who accompanies the titular detective on bizarre -LSB-...] (flickeringmyth.com)