Katy Perry —
Too good to be true? Before Grammy-nominated pop icon Katy Perry made it big, she was signed by both Island Def Jam and Columbia Records. She was subsequently dropped by both labels and facing financial binds. But breakthrough single "I Kissed a Girl" launched Perry into a skyrocketing career. From performing at the Super Bowl to the Grammys, the award winning artist has made significant strides at just 31 years old.
Steve Jobs —
Imagine getting pushed out of the company you created. During a time of slumping sales, Apple Inc.'s board of directors removed Steve Jobs, who co-founded the tech company. He was hired back years later as interim CEO (with an annual salary of $1), but struggle ensued. Jobs suffered various health complications throughout his career, often resulting in leaves of absence. Even through these setbacks, Jobs prevailed and launched some of the company's most successful products: from the iPad to the MacBook Air. Jobs died of cancer, but his tech empire lives on. 
Oprah Winfrey —
Oprah Winfrey became the youngest and first African-American anchor for WTVF-TV in Nashville at just 19 years old, while still a sophomore in college. Great things were in store, but not without hitting a road bump along the way. Shortly after starting her new job as co-anchor of the 6 p.m. newscast with Jerry Turner, she was publicly fired from WJZ-TV in Baltimore. Oprah overcame the hurdle and eventually went on to become the host of "The Oprah Winfrey Show." A household name and billionaire, among many other successes, Oprah was awarded the Presidential Medal of Freedom by President Barack Obama in 2013.
Bill Gates —
Becoming a billionaire was no walk in the park for Bill Gates. The college dropout turned Microsoft tech tycoon suffered major flops on his road to success, including Windows Media Center, Microsoft Bob, Windows Me and Windows Vista. Gates also dealt with a lawsuit in the late 1990s when Microsoft was sued for antitrust violations by the U.S. Justice Department and European Union. Ultimately, both cases were settled. Gates is now the richest person in the world. He co-chairs the Bill & Melinda Gates Foundation. 
Steven Spielberg —
Many actors dream of the day they get to work in the presence of legendary filmmaker Steven Spielberg, but he weathered a couple of storms to get to there. Twice the Hollywood icon was rejected by University of Southern California's School of Cinema Arts. That didn't stop Spielberg. He went on to become an Academy Award winner, co-creator of DreamWorks, and one of the most highly respected filmmakers in the entertainment industry -- of all time.
J.K. Rowling —
It's not easy to become a world recognized author, but J.K. Rowling defied all odds. The first of the "Harry Potter" novels was written by Rowling in Edinburgh, Scotland, from various coffeehouses while her daughter napped. They were living off public assistance. When the "Harry Potter" series took off, Rowling later dealt with copyright infringement legalities to protect her famous writings. Ultimately, her books became multimillion-dollar box office hits. In 2008, Rowling was given the honor of delivering the commencement address at Harvard, in addition to receiving an honorary degree.