After seven seasons, ABC’s fairy tale mash-up show, “Once Upon a Time,” is ending on Friday. But Colin O’Donoghue — whose role as the smoldering Captain Hook made him the coolest character on the series — didn’t entirely leave it behind.

“I got to keep my pirate costume,” says O’Donoghue, 37. “I think I’ll put it on display in my house. I’ll never say goodbye to leather pants.”

Along with O’Donoghue, “Once” stars Lana Parrilla and Robert Carlyle. The first six seasons also starred Jennifer Morrison, Ginnifer Goodwin and Josh Dallas, all of whom are returning for the series finale (May 18 on ABC).

“I think how [showrunners] Eddie [Kitsis] and Adam [Horowitz] have concluded the series is fantastic, so we’ve done it justice,” says O’Donoghue.

Over the course of its seven-year run helmed by Kitsis and Horowitz (“Lost”), “Once” threw together fairy tale characters such as Snow White (Goodwin), Captain Hook and Rumplestiltskin (Carlyle), giving their stories unexpected twists (e.g., the show’s version of Little Red Riding Hood was a werewolf).

Half the action took place in real-world settings, but each episode also featured “Lost”-style flashbacks to the characters in fairy-tale worlds. Donoghue says he looks back fondly on the show’s version of Neverland.

“Quite a lot of that was shot on the [Vancouver] set, so they had the forest in one of the stages. I also play Captain Hook, so I’m going to say Neverland [was my favorite setting].”

O’Donoghue lives near Dublin with his wife and family. The Irish actor had stints on shows such as “The Tudors” before he joined “Once” in 2012, its second season, and it changed his career.

‘Families could sit down and watch it together. That’s so rare, and it’s something I’m very proud of.’

“‘Once’ brought me to more people’s attention, because it was such a massively popular show,” he says. “I didn’t have social media really before I started the show, and I didn’t know really what Twitter was about, and all of a sudden it exploded.” (He currently has over half a million Twitter followers and over one million Instagram followers.)

While he says he isn’t yet able to discuss what he’s doing next, he’s not sad about the end of “Once.” Rather, he’s proud of its legacy as a show for everyone.

“That’s part of what was so great about ‘Once.’ It went all across the spectrum of age,” he says. “Families could sit down and watch it together. That’s so rare, and it’s something I’m very proud of.”

In the age of superhero TV (“Arrow,” “Jessica Jones”) and gritty genre fare (“Game of Thrones”), “Once” stood out as a genre show that didn’t revolve around superheroes or cater to an exclusively adult audience.

“I’ll definitely miss the show and I’ve thoroughly enjoyed the six seasons that I was on it,” he says. “It was a really special thing to be a part of. I hope it has a legacy. It’s a positive show. It’s about love; it’s about the power of what it means to be open and honest and true to people. There’s always a place for stuff like that in the world. It’s been an absolute joy.”

“Once Upon a Time” Series finale 8 p.m. Friday on ABC