Jeff Washburn is a character who appeared in the first four episodes of Season Five of Silicon Valley. Played by Armen Weitzman.
Washburn first appeared in "Grow Fast or Die Slow", eventually getting hired at Pied Piper. In "Reorientation" he was revealed to be a mole for Hooli.
In "Chief Operating Officer", he agreed to take Dinesh Chugtai as a roommate, ostensibly to help Dinesh make ends meet by splitting the rent. Washburn took advantage of the opportunity by getting Dinesh, an original member of the Pied Piper team, drunk, so as to learn valuable information to pass on to Hooli.
And in "Tech Evangelist", Washburn is discovered, thanks to Bertram Gilfoyle. But Richard Hendricks doesn't want to tip Hooli off, so Washburn is forced to continue sitting at his desk at the Pied Piper offices like nothing happened, and go to events like Battle Bots with Dinesh after work.