Let's start at freshman year. Since Zuckerberg is (well, was supposed to be) part of the Class of 2006, and if we turn the clock back to 2002, we find that he resided in the freshman dorm Straus, room D11. Harvard Dorm History Search tells us that in the year 2002 the fellow residents of Strauss D11 are Samyr Laine, Bede Moore and Justin Coffin. [1] Some Google stalking tells us...
- Samyr Laine's concentration isn't stated anywhere, but what stands out foremost is that he's an Olympic high jumper. Namely, he represented Haiti at the 2012 Summer Olympics and currently holds Harvard athletics' record for highest triple jump. You can read more on his Wikipedia article (Samyr Laine) or one of the many articles about his athletic achievements. Beyond athletics, he's also gone to law school.
- Bede Moore is an Australian crew rower who concentrated in history. According to his LinkedIn profile, he's the owner of an e-commerce company and works in Indonesia now. He also has a personal website (Bede Moore - Home). At one point, he wrote editorials for the Crimson (The Harvard Crimson).
- Justin Coffin started as a Government concentrator but transferred to another school, went to law school, passed the bar and currently works in a law firm, according to his Linkedin profile.
After freshman year, the four part ways. In Kirkland House room H33, where by legend Facebook was founded with roommates Chris Hughes, Dustin Moskovitz, and Eduardo Saverin (each of whom have their own respective Wikipedia page).
[1] Zuckerberg and Coffin don't actually appear in the search results but are listed in this article (Zuckerberg Freshman Roommate Goes From Harvard to Haiti Olympian) I'm presuming that's because they didn't graduate.