Richard Twiss
Richard Twiss is a Mathematician, the T of the HBT interferometer, and the companion in posterity of Hanbury Brown.
It is extremely difficult to find pictures of him. According to Nina Voronova, it is because he was a Soviet spy. She informed me of this publicly, during a talk I was giving showing a picture of Twiss and saying that is the only one I could find. She interrupted me and said: «But it is because he was a Soviet spy!» From anybody else than Nina, I would have thought it was a joke, while for her it was just a trivial consequence of a famous fact (none being obvious to me).
According to Indianara Lima Silva, this is what Twiss looked like: (from [1])
However, according to Google images, it seems the person in question is Premier Richard Hatfield of New Brunswick; if not, then this is a higher resolution image of Twiss:
