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Frankie Jonas – who has his own band, Webline – is called "the Bonus Jonas" by fans of the Jonas Brothers, but he prefers another nickname: "Frank the Tank," Will Ferrell's character in Old School. "I have it engraved on a brass ring I got at Disney World," Frankie told PEOPLE.
Christopher Ciccone – who worked on the documentary Madonna: Truth or Dare – released the tell-all tome Life with My Sister Madonna, in which he blames her husband Guy Ritchie for the disintegration of their relationship. Madonna's longtime rep Liz Rosenberg responded in a statement: "I would have to assume she has come to terms with the fact that [Madonna and her brother] do not have a close and loving relationship. And with the book coming out, I assume that will remove the chances of that ever happening."
Like his sister Tori, Randy Spelling appeared on Beverly Hills, 90210 (as Ryan Saunders), and also in frat-house comedies like Pledge This! and National Lampoon Presents Dorm Daze. He's now known around his sister's house as Uncle Randy, to Tori's children Liam and Stella.
Mandi Gosling is a familiar face on the red carpet, having accompanied her brother Ryan to the premieres of Lars and the Real Girl, Half Nelson, the Screen Actors Guild Awards and more.
In the video for Lindsay Lohan's single "Confessions of a Broken Heart (Daughter to Father)," little sis Ali, then 11, played a young Lindsay. Now 14, Ali's following in her older sister's footsteps in both acting and singing. The making of her album is documented in the reality show Living Lohan, and she's released the single, "All the Way Around."
Bryan Spears, 31, is the big brother to Britney and Jamie Lynn – and has been a big part of their careers. He is a co-trustee to his sister's massive fortune (meaning he keeps tabs on everything she spends), and he co-executive-produced Jamie Lynn's hit Nickelodeon show, Zoey 101.
With his shaggy hair and green eyes, Zac Efron's younger brother Dylan is a hot topic on fan sites and message boards – even though he isn't a TV or movie star! "My brother Dylan really isn't into performing at all," Zac told J-14. "He's a sports guy."
Katherine Heigl was a bridesmaid in her sister Meg's wedding in 2007. And Meg – who was adopted before Katherine was born – returned the favor, serving as matron of honor at her famous sister's 2007 nuptials to musician Josh Kelley.
Rihanna – whose single, "Take a Bow," is the No. 2 song in the country – has two younger brothers, Rorrey, and Rajad (pictured), whom she shared some sweet quality time with at PEOPLE's music lounge last summer.
Hotel heir Barron Hilton recently pleaded no contest to charges that he was driving under the influence in February. He received probation – unlike his big sis, who famously had to serve jail time.
The 2002 MTV reality series The Osbournes turned Ozzy and Sharon's kids, Jack and Kelly, into household names. However, Aimee opted out of the show, asking that her face be blurred every time she was on-camera. "My private life, to me, is very important," she later told Barbara Walters.
Eric and Gwen Stefani started No Doubt together – and cowrote much of the band's breakthrough record, Tragic Kingdom. But Eric soon left the band to become a professional animator, working on The Simpsons and winning an Emmy for the episode "Life on the Fast Lane."
Like her little sis Miley, Brandi Cyrus is also a musician, penning songs for Miley's new disc, and an actress, having appeared – albeit briefly, as a band member – on Zoey 101.