According to the New York Post, the couple met while Williams, a 2010 Yale graduate, was filming the pilot for her hit HBO series.
Van Veen created the popular humor site with high school pal Josh Abramson while a freshman at Wake Forest University in 1999.
According to a 2005 profile in The New Yorker, the friends grew up in Timonium, a suburb of Baltimore, and had known each other since sixth grade.
College Humor began as "a kind of nerdy diversion," where they'd collect jokes and funny photographs.
We don't have one male friend who isn't a little obsessed with Allison Williams.
"It's just something we haven't focused on," said Allison, "but, spoiler alert, we are excited!
creator Lena Dunham, Katy Perry, John Mayer, Bruce Springsteen, Seth Meyers and wife Alexi Ashe, Diane von Furstenberg, Andy Cohen and Tom Hanks and wife Rita Wilson, who plays Williams' mother on the acclaimed HBO comedy.
Williams' co-star Zosia Mamet was spotted arriving at the Denver airport with boyfriend Evan Jonigkeit on Friday.
According to , who first broke the news, Katy Perry, John Mayer, Bruce Springsteen, Andy Cohen, Tom Hanks and wife Rita Wilson and Lena Dunhamwere in attendance before Sunday's Emmy awards. News can confirm Mindy Kailing and Girls co-star Jemima Kirke also attended.
Williams' rep confirmed her engagement to the College Humor co-founder, 34, in February 2014.