The Best Collaborator Billie Eilish Ever Worked With—And Why It Was Never Even Close

In an industry bursting with feature-heavy albums and one-off duets, Billie Eilish has built her empire on something far more intimate: a lifelong creative partnership with her older brother, Finneas O’Connell. While Billie has experimented with a variety of celebrated collaborators—ranging from Khalid to Charli XCX—none have come close to matching the depth, intuition, and musical alchemy she shares with Finneas. And by all accounts, she wouldn’t have it any other way.

Together, the sibling duo crafted Eilish’s first breakout EP Don’t Smile at Me and the Grammy-sweeping debut album When We All Fall Asleep, Where Do We Go?—projects that not only launched Billie into global stardom but also reshaped the landscape of pop music. Their chemistry is unmatched, manifesting in genre-defying tracks like “Bad Guy,” the intimate “Everything I Wanted,” and the Oscar-nominated “What Was I Made For?” from Barbie—all co-written and produced in bedrooms and home studios rather than billion-dollar studios.

“He knows me better than I know myself,” Billie once said in an interview, explaining how their trust and shared vision allow them to push creative boundaries without fear. That comfort zone doesn’t equal complacency—it fuels evolution. Their latest release, Hit Me Hard and Soft, continues to showcase their ability to blend atmospheric textures, raw emotion, and lyrical introspection in a way no outside producer ever could.

That’s not to say Billie hasn’t thrived in other musical partnerships. Her haunting ballad “Lovely” with Khalid became a viral sensation and an emotional anchor for millions of fans. Her team-up with Rosalía on the Spanish-language track “Lo Vas a Olvidar” stunned with its emotional subtlety and cross-cultural resonance. In 2024, her remix of Charli XCX’s “Guess” topped international charts and earned a Brit Award. And with Vince Staples, Billie explored bold hip-hop territory on the gritty “&Burn.”

Yet, even amid these high-profile successes, one collaborator towers above the rest: Finneas. He isn’t just her producer—he’s her mirror, her sounding board, her co-architect in crafting music that defines a generation. In a music industry built on ephemeral features, Billie and Finneas are a reminder that the best collaboration is sometimes the one that never ends.