Nathaniel Borenstein
This adorable photo of his barbershop quartet, The Telephone Chords.
The extension that Borenstein and his fellow researcher, Ned Freed, wrote back in 1992 (called Multipurpose Internet Mail Extension) is still used for every email attachment today.
They created it because Borenstein said that he one day dreamed of being able to receive pictures of his grandchildren over email.
Head over to Quartz for a Q&A with Borenstein about Bitcoin and security, in honor of the web's 25th birthday.