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NBC Insider The Tonight Show Starring Jimmy Fallon

Oscar Isaac Sang Jimmy Fallon a Hippopotamus Song He Wrote for His Sons

The actor and musician serenaded the Tonight Show Host with an original tune he wrote for his son Mads.

By Samantha Vincenty
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From the Star Wars franchise to Dune, Oscar Isaac has starred in several blockbusters over the years, as well as fronting a Marvel series. But he's also an accomplished musician — but he showcased his skills during a 2021 visit to The Tonight Show, serenading Jimmy Fallon with an original "Hippopotamus song" lullaby he wrote for his sons, Mads and Eugene.

How to Watch

Watch The Tonight Show Starring Jimmy Fallon on NBC weeknights at 11:35/10:35c and next day on Peacock

Isaac's first big starring role was in 2013's Inside Llewyn Davis, where he used his real voice and guitar talent to bring the film's titular folk singer to life. In January 2024, he even duetted with Grammy-winning Guatemalan singer-songwriter Gaby Moreno on The Tonight Show stage (and who can forget his sweet duet with fellow meatball Charli XCX in this Saturday Night Live sketch?).

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Fallon stashed a guitar for just the right moment in their interview — but ahead of that, Isaac talked bonding with his Dune co-star Timothée Chalamet (who's himself playing real-life folk singer Bob Dylan in the upcoming A Complete Unknown). 

"We played a lot of music. We did," Isaac said of he and Chalamet, who was prepping to take on the Bob Dylan role at the time. "He was playing a lot of guitar at the time, so we'd trade some songs."

"I was going to say, did you play him any lullabies that you play to your son?" Fallon joked.

Oscar Isaac plays the guitar to Jimmy Fallon on The Tonight Show Starring Jimmy Fallon Episode 1537.

Oscar Isaac sings Jimmy Fallon the "Hippopatamus song" he wrote for sons Mads and Eugene

While Isaac didn't play Chalamet any lullabies during their jam sessions, he shared that he's composed a few originals for Mads and Eugene, his sons with wife Elvira Lind.

"What are the originals?" Fallon asked him.

"You know, 'Elephants Are Kind to People,'" Isaac offered, as the audience giggled. "The Hippopotamus Song, the little guy is really into — and I feel like he's coming around to it now, the older one."

Fallon just so happened to have a guitar behind his desk, and requested the Hippo song. Isaac happily obliged.

Isaac's ode to "the most dangerous animal in the world" includes lyrics like, "♪ I'm a hippopotamus ♪ 5:21 ♪ I like swimming, but I'm dangerous ♪ 5:24 ♪ If you get too close to me ♪ 5:26 ♪ I might just bite your feet!"

Watch Isaac's hippo number above.