Irish actor Brendan Gleeson made his film debut in 1990’s “The Field,” starring Richard Harris and based on the play by John B. Keane. Five years later, he made an impact internationally as Hamish Campbell in Mel Gibson’s Oscar winner “Braveheart.” Since then, film lovers have seen the versatile thesp in a wide range of blockbusters and indie films. “Harry Potter” aficionados know him as Alastor “Mad Eye” Moody, and fans have treasured his work in such fare as John Boorman’s “The General,” John Michael McDonagh’s “Calvary” and Martin Scorsese’s “Gangs of New York” and for his Emmy-winning turn as Winston Churchill in TV film “Into the Storm.”

Now on-screen as Detective Bill Hodges in the new Stephen King neo-noir TV series, “Mr. Mercedes,” Gleeson was first noticed by Variety on Aug. 1, 1990, for his performance in Dublin in Keane’s play “The Year of the Hiker.”

John B. Keane’s work as a playwright was popular, but it probably took “The Field” to bring his work to foreign audiences.

Yes, Keane defied the critical opinion of the time. He brought a very rural sensibility to the theater, and I think his rural background, especially in regards to his female characters, was at odds with the time. He sort of saw women as different creatures than men. That said, I did another Keane production with actress Marie Mullen, and I was just staggered by her performance.

In 1990, you were 35 but had only recently chosen acting as your primary vocation.

I was teaching English and Irish at the secondary school level and I actually enjoyed it, but in the summer of 1989 I was working at the Tivoli Theatre and the Olympia Theatre in Dublin, and I was making a little bit of money.

You were in your 30s, and you had a family. Was there pressure to “keep your day job”?

My wife, Mary, is very levelheaded, and she encouraged me. She was incredibly supportive. We both felt it was time to make the jump, and she went back to work at the Abbey Theatre in the first few years to make sure the family was taken care of. Also, I believe she just couldn’t look at me anymore.

Did teaching school yield any dividends for your work as an actor?

At first, I tried to treat students reasonably, like they were human beings. And they ate me alive. So I did learn to keep my distance. I learned that it’s a bluff.

So dealing with rowdy schoolboys prepared you for Hollywood?

My general impression of the entertainment business was positive. I had been warned. I heard all the stories of backstabbing. And all of the networking that I was told was required was definitely not what I wanted to do. My biggest fear in the early days is that I’d spend my life sitting on the couch waiting for the phone call. I was afraid I would get in the position of doing anything for the money, that I’d get taken in by the system, but that crisis of integrity never happened.

But “The Field,” “Braveheart,” “Michael Collins” and “The General” and many other terrific films happened.

Speaking of “The General,” I probably learned more from working with director John Boorman than anywhere else. Working with the master was a guide to film acting.