But this year, Zuckerberg has been thrust into pop culture ubiquity, appearing on screens of all shapes and sizes, from "Oprah" to one of the year's most acclaimed films.
On Wednesday, his public ascent was solidified by Time magazine, which named him its "Person of the Year." He's the youngest choice for the honor since the first one chosen, Charles Lindbergh in 1927.
In a posting - where else? - on his Facebook page, Zuckerberg said being named Time's "Person of the Year" was "a real honor and recognition of how our little team is building something that hundreds of millions of people want to use to make the world more open and connected. I'm happy to be a part of that."
Image: This image released by Time Magazine on Dec 15, 2010, shows the cover for Time magazine's 2010 "Person of the Year" issue, featuring Facebook founder and CEO Mark Zuckerberg. (Photograph copyright AP)