“Finding Dory” brings back a lot of familiar faces from “Finding Nemo” – but if you’ve seen the movie, you know some of the newer characters steal the show.

One such character doesn’t even have a face, as she’s just a disembodied voice: As the fish travel to the Marine Life Institute (“the jewel of Morrow Bay, California”) to find Dory’s parents, they’re welcomed by the soothing sounds of one Sigourney Weaver: “Hello, I’m Sigourney Weaver,” the recording starts, as the famed actress welcomes all visitors to the family-friendly aquatic center.

Weaver’s voice booms through the movies at the most unexpected times, and is a running joke through the whole film, especially considering that all the animals (including Dory and the sea lions) come to consider Weaver their pal. It’s just random enough to be hilarious. But how did Weaver end up in the film?

Director Andrew Stanton laughed when asked the question. “Yeah, it’s just so specific,” he agreed. He pointed out that Weaver is the “default voice” for nature footage, as she can be heard in “Planet Earth” and at the California Academy of Sciences in San Francisco during a planetarium show. “It just cracked us up.”

In fact, Stanton said, he thought the Weaver bit was definitely going to get axed because it was so weird. But her voice just kept getting a bigger and bigger role. Eventually, when it became clear that it was actually going to make the final cut, he had to hurry and ask Weaver if she could actually voice the part. (Luckily, the two knew each other already from when Weaver voiced a role in Stanton’s “Wall-E,” and she said yes.)

“God bless her, she was really in on the joke – she just thought it was a hoot that she could play herself. It kind of gets funnier each time it’s said,” Stanton said. Still, he admitted that it’s possible not everyone will understand the gag: “I’m not sure how that’s going to translate in other countries. I’m not sure if they’ll stick with her, or just go with their local person who does nature videos and things.”

Meanwhile, Ed O’Neill (of “Married ... With Children” and “Modern Family” fame) also becomes a favorite as Hank, the grouchy octopus who just wants to call it a day and be transported to the Cleveland aquarium, where no annoying children will bother him. He was Stanton’s first choice from the beginning to voice the character.

“I watch a lot of ‘Modern Family’ and I really like him,” Stanton said. “Without visuals, Ed still sounds like this gruff curmudgeon you can sense still has a heart of gold and is soft on the underbelly. And that’s what I needed for Hank.”

Indeed, Hank winds up an important character who helps out Dory, Marlin and Nemo when they need it most – and O’Neill’s voice captures it perfectly. Luckily, Stanton said, he had that experience with casting almost every character.

“One of the real perks when you’re doing a sequel to a hit movie is all the agents return your phone calls,” Stanton joked. “So all my first choices are pretty much who you hear in the cast.”