Famous Monsters #18
The mystery was solved many years ago, but I thought you'd like to look at the pictures anyway.
Because the subject of Gogos' painting (with added pointy ears) was misidentified (in this issue, as well as previously in issue #1), it was believed by many to be Frye for some years after.
The man behind the painting was, in fact, Bernard Jukes (1900-1940), who had played "Renfield" in the Hamilton Deane (and John L. Balderston) stage adaption of Dracula, in both the London cast (with Raymond Huntley as "Dracula") and New York cast (with Bela Lugosi).
When the Universal film adaption was announced (with Lugosi and Edward Van Sloan repeating their roles as "Dracula" and "Van Helsing"), Jukes lobbied hard for the role of "Renfield" and had several photos taken of himself in character (see below), but the part went to Dwight Frye. Jukes continued playing "Renfield" in stage productions of Dracula (some produced by him) until his death in 1940.