Billie Eilish Pens Birthday Tribute to Brother Finneas O'Connell: "My Best Friend Forever"

Billie Eilish and Finneas O'Connell are pretty much living proof that siblings can make the best musical collaborators. The brother-sister duo — who don't share last names in the professional world since Eilish uses a stage namehave been making music together for most of their lives, and they're still rocking out together. In addition to being musical collaborators, they've always been incredibly close and frequently share love for one another. On July 31, for example, Eilish wished her brother happy birthday in a sweet Instagram post that reads, "my best friend forever. will never love anyone as much as i love you @finneas happy birthday you are the best thing i have."

The pair have paid tribute to one another many times through the years, and in 2019, while accepting Variety's hitmaker award, Eilish opened up about just how much her brother means to her. "A big thank you to my big brother Finneas. Finneas is my best friend, my big brother. He's four years older than me and we've been best friends forever," she said during her acceptance speech. "We started making music together when I was 13 and he was 17; he produces everything. He's the only reason I'm anywhere in the whole world and he's probably the only reason I'm alive." O'Connell also shared similar feelings in his part of the speech. "There's a lot of bullsh*t articles about me now, about how I'm not just Billie Eilish's brother," he said. "Just being Billie Eilish's brother is all I ever wanna be. I love Billie more than anything else and I'm so grateful to you and I love you."

While Eilish is a verified megastar, O'Connell also has his own successful career as a singer, songwriter, and music producer, and he's had a hand in making plenty of hits. Even as their careers have taken off, the siblings have been at each other's sides all the while. Ahead, check out some of the best pics of the duo together that will make you want to call your own siblings pronto!