Cavan Scott (in-universe)

Cav (PROSE: Party Fears Two) was a bespectacled man who attended Brenda Soobie's party in Las Vegas 1967, San Diego Comic-Con, and the Stardreamer II.

Biography
Cav, along with Stew, attended Brenda Soobie's party in Las Vegas 1967, where they talked to both Phils and Hilary. (PROSE: Party Fears Two)

The Twelfth Doctor took a selfie with the same man at San Diego Comic-Con. (COMIC: Selfie)

A similar bespectacled man was a party guest on the Stardreamer II. (COMIC: Secret Agent Man)

Behind the scenes
Cavan Scott was the author of both comic stories he cameoed in.