A B-list star. One who is visually recognizable but whose name is not top of mind.
I sat next to a sublebrity at dinner, I think it was Eric Roberts.
A so-called celebrity who no one has really heard of, despite occasionally appearing on the news or in a newspaper in a story that has no real relevance to our lives in any way whatsoever.
News Reporter: "Paige Railton and Nathan Lorel have just had a baby"
Person 1: "Who?"
Person 2: "Probably just some Sublebrity"