R. F. Wilburton

 was the associate curator of the Repository of the Improbable on the Braxiatel Collection.

He told Bernice Summerfield that he was a victim of a of events, which made it impossible for others to see him. He wasn't invisible; people just got distracted when trying to see him. Benny was sceptical of this claim, but while talking to him she never did see him, getting distracted often during the conversation. (PROSE: The Door into Bedlam)