Marcel Proust

By 1919, Proust rarely left his soundproofed Paris apartment, complete with a bedroom encased in walls of cork to keep out noise. He worked in a sunless writing studio with the window shut as protection against the asthma that had plagued him since the age of 9. The isolation took its toll. The writer Leon-Paul Fargue recalled Proust around this time as pale, with hands that seemed frozen. "He looked like a man who no longer lives outdoors or by day, a hermit who hasn't emerged from his oak tree for a long time," Fargue wrote.

David Plouffe

Strategic and unemotional, Mr. Plouffe comports with Mr. Obama’s exacting style and natural reserve (“very, very, very, very, very, very private,” Mr. Daley said of Mr. Plouffe and Mr. Obama—six verys).

The Wachowski brothers

And then there's the filmmaking Wachowski siblings, one half of whom (Larry) now lives as a woman (Lana), and neither of whom has uttered an audible peep since well before beginning their blockbuster Matrix trilogy over a decade ago. Yet both recently, bafflingly appeared in photos tweeted by Arianna Huffington from the set of their latest film.

Emily Dickinson

Although she became known as an eccentric recluse and was called "the woman in white" (because she almost always wore a white dress) by the people in Amherst, Dickinson must have seemed more curious than terrifying. Local children enjoyed it when she lowered treats and snacks out her second-floor bedroom window inside a basket tied to a rope. Usually they would only glimpse her hands and arms, as she was careful not to show her face.

Stanley Kubrick

[Kubrick] was also rarely photographed, so that even at the height of his career, many fans didn’t know what he looked like. This allowed Alan Conway, a con man, to go around the UK impersonating Kubrick for quite some time, gaining entrance into parties and nightclubs. The story is the subject of 2007’s Color Me Kubrick, starring John Malkovich.

J. Edgar Hoover

On May 1, 1972, Helen Gandy, Hoover’s personal secretary, handed him the first in a series of exposés by Jack Anderson, whose column appeared in the Washington Post. Previously, Anderson had enraged Hoover by assigning a reporter to rummage through his trash at home. The resulting column revealed that on Sundays, Hoover ate a hearty breakfast of poached eggs and hotcakes. It also revealed that he brushed his teeth with Ultra Brite, washed with Palmolive, and shaved with Noxzema shaving cream.