She has been a part of people's lives for more than two decades, hosting her own talk show, publishing her own magazine and launching her own cable-television network.
Oprah Winfrey has succeeded in just about everything she has touched in the past 25 years, but is it enough to call her one of the most influential people of the last two decades?
CNBC turns 25 this year and is asking readers to help come up with the 25 most influential leaders of the past 25 years based on a list of 200 nominees.
Among the entertainment names on the list, Oprah is No. 1 so far in the voting, followed closely by Ted Turner, founder of the cable news channel CNN, and "Star Wars" creator George Lucas. "Harry Potter" author J. K. Rowling and media mogul round out the top five in entertainment.
(Read more: JK Rowling: Nice books, but not that important)
Ilene Cooper, author of "Up Close: Oprah Winfrey," isn't surprised by Winfrey's lead.
"I think she obviously was a dominant figure," said Cooper. "I think she broke a lot of barriers when she started in Chicago in the early '80s. It was unheard of—she was the host of a show, she was African-American, she was a woman and she was overweight."
Over the years, people have been able to identify with Winfrey, according to Cooper, because they witnessed her struggles to succeed in a male-dominated industry.
"25 years ago, the things she was trying were incredibly innovative," she said.
But not everyone agrees.
What she was doing was successful but it wasn't revolutionary, said Robert Thompson, director of the Bleier Center for Television & Popular Culture at Syracuse University. Yes, she broke ground for women and African-Americans, but she wasn't reinventing media. She was using traditional media—television, magazine, etc.
"What she did was pretty old school," Thompson said.
Thompson said he thinks there's a blurring between influential and famous.
"I'm not sure a single human being can embody the biggest change," Thompson said. "The biggest change is the technological factor."
"Certainly she was successful and it was an Oprah generation. But if you compare what she did to the massive power that are Netflix, YouTube and Twitter ... they are really transforming the entertainment industry."
(Read more: CNBC 25 face-off: Oprah Winfrey vs. Martha Stewart)
The entertainment industry has profoundly changed since 1989, more so "than it has in the first 25 years of the development of motion picture," according to Thompson.
With the development of the Internet at the beginning of the 1990s, people were able to consume entertainment programs in an all new way. The online digital distribution blossomed with the arrival of social media, such as Facebook or Twitter, and the multiplication of streaming websites, such as YouTube, Netflix or Hulu.
"What we are watching is Netflix going from brand new to the new orthodox," said Thompson.
But the Internet wasn't the only revolutionary tool in entertainment in the past 25 years. We also saw the birth of digital video recorders, portable video devices and high-definition television that changed how and when people viewed programs.
If pressed to choose just one person, Thompson said Turner would probably be the one because he created a new kind of news distribution.
"CNN did not become the place you go to for breaking news until 1991 and the Gulf War," Thompson said. "CNN was kind of the new revolutionary ... very exciting!" he said.
Who are your picks for the 25 most influential leaders of the past 25 years? Click to cast your vote.
—By CNBC's Mathilde Hamel. Follow her on Twitter @mathildehamel