The star of BBC America's crime drama also explains why the show's approach to tragedy has such an effect on audiences.

Of all the roles that David Tennant has played, Detective Inspector Alec Hardy in “Broadchurch” is perhaps the least likely to be associated with a catchphrase — and yet he has one. Or, at the very least, he acknowledges that when you think of Hardy, you think of him shouting “MILLAH!” in a strong Scottish accent.

It has significance to this reporter, given my byline, which was something I mentioned to Tennant when we spoke about the third and final season of the ultra-serious drama series. “I’m delighted,” he said when I told him how much I enjoyed the “MILLAH!” meme. “People shout it at me in the streets sometimes, actually,” Tennant said. “Which is a bit odd because it’s not actually my name. But it obviously pleases people for some reason.”

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Tennant acknowledged that when you think about shows which might inspire catchphrases, “Broadchurch” is “not that type of show at all.” The dark and emotional series, created by Chris Chibnall, technically revolves around the horrific crimes investigated by Hardy and his semi-regular colleague Detective Sergeant Ellie Miller (the wonderful Olivia Colman, at whom Tennant is often shouting). Unlike your ordinary crime procedural, “Broadchurch” will focus on only one or two separate investigations over the course of many episodes. Over three seasons, that structure has put the focus on not just the question of whodunit, but how those affected are trying to survive the trauma that comes after.

Tennant and Colman are the focal points of “Broadchurch,” but over the course of three seasons they’ve been joined by an impressive array of notable actors, including Arthur Darvill, Phoebe Waller-Bridge, Charlotte Rampling, Lenny Henry, Eve Myles, Sarah Parish, Marianne Jean-Baptiste, and James D’Arcy. Below, Tennant reveals what it’s like to work with a cast on this level, why everyone involved isn’t fighting the decision to end the series with its third season, and how he dealt with bouncing between playing Hardy on “Broadchurch” and Scrooge McDuck on “DuckTales.”

What has the experience of “Broadchurch” been like? Because it’s been a part of your life for several years now.

Yeah, it’s sort of gone on and on. When we first got involved, it was a one-season deal. There was no notion that we were going to make any more. And then the first one just took off in a way that no one really saw coming, and Chris rather shyly says, “I could probably make this a trilogy, I’ve sort of got the stories in my head,” and we all said, “Well, oh OK, great.” Very happy to come back to this world and these characters and this particular way of telling stories, actually.

Because it’s not really like much else. It has a sort of peace to it and a way of examining characters that you don’t often get in TV drama. I don’t know in the U.S. — and this is just, of course, self-centered egotism — but I do often see things coming on the TV in the U.K. and thinking, “That’s a show that wouldn’t exist before ‘Broadchurch.'” It feels like it’s had an influence and I think that’s just because Chris created something very new and at the same time recognizably truthful and honest and something that just caught the public’s imagination. I’m hugely grateful to have been part of that story.

What’s so striking about it as a show is how everything is so grounded in humanity.

That’s a lovely opinion. I think that’s true. It’s not just about crime, it’s always been about the aftermath of crime and how that affects the lives of the people that are left behind. I think that’s always been an equally important element to the show, as the mechanics of the whodunit, which is undeniably a huge part of it, too. But it matters more because you’re invested in the cost of the crime that has taken place and the way that has wreaked havoc on people’s lives and the community’s life. And I think that’s been the great brilliance of the script, of all the scripts. I think it’s also what makes it live. The psychological veracity of it is really important. I think it’s what made us all so excited to sign up for the show in the first place. Not only was it a cracking thriller, but it was full of these characters that you could absolutely recognize and invest in. I think that’s when drama really comes to life.

Also, looking back at everyone who’s been a part of the cast, the fact that they’re all amazing talent in their own right is really impressive.

Oh yeah, it’s always managed to attract the most fantastic actors — all people you would expect to lead a TV show in their own right, and it’s been a real privilege to be amongst that. From Olivia and I’s point of view, we’ve always felt kind of smug because we got to act with everyone. We got to see everyone do their bit. And that was always such a pleasure actually, and we just really enjoy the “Oh, we’ve got so and so coming in to be interviewed today.” To get to play those scenes with some of the fabulous actors that we’ve had, some really well known faces, and then some brand new talent as well, you think these are people we’re gonna be seeing a lot of in the future. It all comes down to Chris Chibnall’s writing because that’s what attracts actors. Good writing is what makes people want to come to work. That’s how you get people who might more normally be leading series in their own right coming and playing juicy supporting roles because they can’t resist it.

Those interrogation scenes in particular must be part of the fun. When you know that you have one of those on the call sheet in the morning is that a fun day to show up at work?

Well of course, they can be quite grueling as well because they’re also very long scenes. They’re often very wordy scenes, and they’re often quite emotionally charged, so they’re not easy days at work. But they’re days that are very exciting because they’re often the dramatic turning points of the story and everyone is on their mettle to do their best work, and that’s very exciting to be around.

While you were working on “Broadchurch,” were you also popping in on other projects? Because you have a lot going on right now…

It’s quite intense, for Olivia and I. We’re in pretty much, not every single hour of every day, but we’re in it quite a lot. There’s not a lot of opportunity for any other big projects. I mean, I’d be doing the odd session of “DuckTales” or something, but it was a pretty intense few months.

What is it like bouncing between “Broadchurch” and “DuckTales?”

[laughs] Well you know, you just sort of do it, don’t you? You just kind of do the job that’s in front of you I suppose. You just find the tone. It’s all about finding the tone, I think.

Are people talking to you about a Hardy and Miller spinoff?

Ehm, I think that if something has the great fortune to be a success, I think there’s always inevitably talk of taking it further and doing more with it, but that was never the intention. Initially, we only thought we were doing one series, and when that expanded, it was, “We’ll do another two seasons and then that’s it.” There was always the expectation that we wouldn’t overdo it simply because there’s a plausibility issue. It’s a small town in the west of England, there just wouldn’t be that many appalling events going on there. After a certain point you’ve got to accept that that would stretch credibility.

For the sake of the truthfulness of the situation, we had to kind of walk away from it. I think the danger is it would impinge on the veracity of those characters, and I think that would be a real shame. So I don’t think anyone seriously talks about there being any kind of spinoff because I think we all know that that’s not what should happen. Certainly not anytime soon.

Is it nice to have the idea of an ending?

Yeah, of course. It’s nice to know that you’re choosing to walk away from something rather than the enthusiasm for it evaporating and having to shuffle off because nobody wants you anymore. And I think it’s quite good to stick to your guns on that, to not go “Oh, OK. One more season then.” For something that’s been such an important part of all of our lives, personally and professionally, I think it’s nice to know that you’ve served it well and you can walk away with your head held high. So I think right now, everyone feels like “Job well done, let’s not meddle.”

Beyond “Broadchurch,” it seems like you’ve gotten to do so much in recent years. Is there anything you haven’t done yet that you really want to do, something you’re looking forward to doing?

Well, you’re sort of always looking for the next thing, and you never quite know what that thing is until it presents itself. I don’t really think particularly tactically in terms of career choices, I sort of bumble from one to the next and I’ve been so far quite lucky that they’ve added up. I seem to be sort of managing to have a variety of different things, which seems to keep me happy.

“Broadchurch” Season 3 premieres Wednesday, June 28 at 10 p.m.

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