Venus and Serena Williams | There's plenty of sisterly love between these gold medalist tennis superstars. "I always like to win. But I'm a big sister. I want to make sure she has everything, even if I don't have anything," Venus said.
Photo Credit: All Star Tennis Charity Event at Cliff Dysdale Tennis Center; Larry Marano/Getty Images
Mary-Kate and Ashley Olsen | The world was introduced to the Olsen twins on "Full House," and they went on to have a successful entertainment career. They also work together on their couture fashion label, "The Row." Together, their net worth is estimated to be $300 million.
Photo Credit: Costume Institute Gala at the Metropolitan Museum of Art, 2014; Dimitrios Kambouris/Getty Images
Elle and Dakota Fanning | The Fanning sisters may occasionally get mixed up from time to time, but that's only because they've both had equally successful film careers since their childhood.
Photo Credit: Louis Vuitton Show at Paris Fashion Week Spring/Summer 2014; Petroff/Dufour/Getty Images
Beyoncé and Solange | Aside from their separate music careers, they've collaborated on their family clothing line, House of Dereon. "I admire her, and though she's five years younger than me, I strive to be like her. She's so smart and secure. She's sensitive to people's feelings, but not afraid of what they think," Beyoncé said about her sister Solange in an interview with ESSENCE in August 2003.
Photo Credit: 2015 Vanity Fair Oscar Party; Kevin Mazur/VF15/WireImage
Kate and Rooney Mara | Younger sister Rooney earned an Academy Award nomination for her role in "The Girl with the Dragon Tattoo" while older sister Kate rose to fame as Zoe Barnes on "House of Cards." Their family history also has strong ties in sports: their great-grandfathers, Tim Mara and Art Rooney Sr., founded the New York Giants and the Pittsburgh Steelers.
Photo Credit: Netflix's "House of Cards" New York premiere, 2013; Dimitrios Kambouris/WireImage
Taissa and Vera Farmiga | "Taissa is the person you take with you to choose your Oscar gown and then take to In-N-Out Burger. As much of an age difference as there is (21 years), she is one of my best friends in the world," Vera said about her younger sister in a Teen Vogue interview.
Photo Credit: "The Judge" Los Angeles premiere, 2014; Gregg DeGuire/WireImage
Kate and Pippa Middleton | Kate is busy tending to her young children, Prince George and Princess Charlotte, while her sister Pippa continues to pursue her media career.
Photo Credit: Wimbledon, 2012; Clive Brunskill/Getty Images
Tia and Tamara Mowry | "The coolest thing is that my sister and I, you know, we’ve done what a lot of people have not been able to do. Which is to have our own careers, together," Tia said.
Photo Credit: KIIS 102.7 and ALT 98.7 FM pre-Grammy party and lounge, 2014; Tibrina Hobson/WireImage
Penelope and Monica Cruz | When Penelope's not gracing the silver screen, she's working with her sister to design lingerie for L'Agent by Agent Provocateur and a clothing line for Mango.
Photo Credit: Opening of the 1st L'Agent by Agent Provocateur London Boutique, 2015; Darren Gerrish/WireImage
Joan and Jackie Collins | Joan Collins is best known for her role in "Dynasty" and her role in the TV series "The Royals." Her sister Jackie is a New York Times best-selling author.
Photo Credit: Vanity Fair Oscar Party, 2015; Anthony Harvey/Getty Images
Jessica and Ashlee Simpson | The Simpson sisters had successful careers as pop singers in the 2000s and Jessica has ventured into her own fashion line. Lately, they're both focused on their growing families.
Photo Credit: Jessica Simpson Collection event, 2013; Jamie McCarthy/Getty Images for Jessica Simpson Collection
Hilary and Haylie Duff | Once upon a time, the Duff sisters co-starred in the comedy "Material Girls." Aside from their separate entertainment careers, they’ve come together to take part in charity events.
Photo Credit: Los Angeles Mission's 75th anniversary year end of summer block party, 2011; David Livingston/Getty Images
Malia and Sasha Obama | Malia and Sasha may share the spotlight with POTUS and FLOTUS but they've been able to reveal their dynamic personalities while growing up in front of the whole country.
Photo Credit: TNT Christmas in Washington 2014 at the National Building Museum; Theo Wargo/WireImage
Kate and Laura Mulleavey | Fashion designers Kate and Laura Mulleavey founded and run Rodarte together. These sisters are also fellow MAKERS!
Photo Credit: Rodarte Book Launch Party at Curve Boutique, 2014; Andrew Toth/Getty Images