Even after embodying the awkward but likeable Harry Crane for five seasons (and counting) on AMC’s “Mad Men,” Rich Sommer knows the ’60s will have to come to an end eventually, so he’s girding himself for the inevitable day when he leaves the offices of Sterling Cooper Draper Pryce for good. The actor has augmented his growing resume with guest spots on TV shows like “The Office” and “Ugly Betty” and appearances in web videos for “Funny or Die”; he is now in New York rehearsing for this summer’s Broadway revival of “Harvey,” while also attending the world premieres of his new films “Fairhaven” and “The Giant Mechanical Man” at the Tribeca Film Festival. In the final chapter of my three-part Q&A with Sommer, I asked the actor about preparing for life after “Mad Men,” how fictional onscreen friendships become real off-screen relationships, and his tweet heard ’round the world.

Read part three of our three-part Q&A at Backstage.com.