This is your first-ever TV comedy series, apart from guest roles. What inspired the change?
I worked with Seth on American Dad! and loved that experience. Playing Deputy [CIA] Director Bullock opened up opportunities for me I hadn’t had before. Playing an obnoxious, loud, opinionated, vulgar-minded, self-obsessed character was just fantastic.
Your most iconic roles–Captain Picard in Star Trek: The Next Generation, Professor X in the X-Men films–are quite saintly. In the first episode, Walter drives drunk, gets high and picks up a prostitute.
He does mean well. Because he’s essentially a serious and decent man, it makes the outrageousness of the comedy sequences that much more fun to play. There is so much potential for something distasteful to happen. Instead, the scene has a sweetness and charm about it.
You shadowed Jon Stewart and Rachel Maddow to prepare for the role. What did you take away from the experience?
It’s the details. In the production offices, there are children’s drawings everywhere. People have families–their children do drawings, and they stick them up. That was an idea I took back, having my grandchildren do drawings and paintings. They’re now on TV.
Are you a news junkie yourself?
I’m addicted to newspapers. I can’t throw a newspaper out until I’ve looked at every single page. My very first job when I was 15 was working on my local paper. All I got to do were deaths, births and marriages. One morning I saw three dead bodies before lunch and went back to the newsroom and said, “I don’t think I can do this.”
This appears in the August 31, 2015 issue of TIME.