Creating the most popular product of the year will make consumers and investors happy. But making an all-time bestseller can transform an industry and define a business for decades.

Many of the best-selling products were first in a new category. Apple (NASDAQ: AAPL), which has sold more than 500 million iPhones, was the first to introduce a touchscreen smartphone that could seamlessly handle music, web browsing and phone calls.

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Other bestsellers took a niche market and made it mainstream. Before Star Wars, film was either comedy, romance or drama. The Harry Potter book series was so successful that The New York Times Book Review created a separate children’s bestseller list in 2000 so account for the series’ popularity.

In some cases, top-selling products were a simply better than their competitors. Before Sony (NYSE: SNE) PlayStation, video game consoles were largely cartridge-based. With the advent of the PlayStation, which relied on the new CD-ROM format, game files could be large enough to support 3D gameplay and full-motion video. Lipitor, which has become the world’s best-selling drug with $141 billion in sales, was far more effective than previously-released drugs at lowering bad cholesterol.

A number of these products continue to be dominate their markets. The iPad remains the world’s best-selling tablet, with a 32.5% market share last quarter, despite challenges from Amazon.com’s (NASDAQ: AMZN) Kindle Fire and Samsung’s Galaxy tablet lines. The PlayStation 4 has sold over 7 million units since it launched last year, well above the Microsoft (NASDAQ: MSFT) Xbox One.

Despite their success, some of these products face challenges. Sales of Pfizer’s (NYSE: PFE) Lipitor dropped each year after its maker, Pfizer, lost patent protection on the drug in 2011 and cheaper generic drugs came on the market. The ongoing Star Wars saga may lose its status as the all time best-selling movie franchise to Walt Disney’s (NYSE: DIS) Marvel Franchise. The Avengers broke box office records, grossing $203.4 million on its opening weekend.

To determine the best-selling products of all-time, 24/7 Wall St. reviewed categories of products widely purchased by consumers and identified individual products that had the highest sales in their category.In some cases, we gathered figures from multiple sources and estimated the final sales figure. In other instances, where one company had a clear market lead, figures reflect data from previous years.

These are the best-selling products of all time.