
MacArthur completed his high school studies at Deerfield Academy. After this, he joined Bowdoin College to pursue a Bachelor’s in Government. To pursue his interest in acting, he later enrolled in Groundlings Theater Company and Atlantic Theater Company, too.
He made his feature film debut with Homo Erectus, portraying Thudnik. However, he is most widely known for playing Jay Geils in Angie Tribeca. His other acting credits also include Go On, Worst Week, A Haunted House 2, Being Frank, and others. He also made guest appearances in popular shows like How I Met Your Mother and Happy Endings.
—via yahoo movies

A Haunted House 2
2014 · as Ned

The Game Plan
2007 · as Kyle Cooper

She's Out of My League
2010 · as Ron

Life As We Know It
2010 · as Peter Novak

The Babymakers
2012 · as Leslie Jenkins

Are We Done Yet?
2007 · as Jimmy the Bartender

Dear Santa
2024 · as Bill Turner

Bachelorette
2012 · as Dale Beaumont

The Way Back
2020 · as Eric (uncredited)

Super Troopers 2
2018 · as Mountie Podien

Director's Cut
2016 · as Reed

I'm Just F*cking with You
2019 · as Chester

Lower Learning
2008 · as Digdug O'Shaughnessy

A Love Like This
2026 · as Paul

The Motel Life
2013 · as Officer Cook

Homo Erectus
2007 · as Thudnik

Prep & Landing
2009 · as Thrasher (voice)

Someone Marry Barry
2014 · as Rafe