The public platform and high profiles of major celebrities can offer tremendous opportunity.

When handled well, people can promote charitable causes they’re connected to, shill for big companies, or go into business for themselves — attaching their money, name, fame and time to new ventures, some of which can take off big-time.

It may come as a surprise, but many A-list celebrities have helped spearhead businesses that have cornered niche economic markets and provided unique services to consumers and the world at large. Here’s a look at five celebrities who have started successful and unique businesses.

1.) Gwen Stefani. Wearing glasses can be hard for some kids, and singer Gwen Stefani recently introduced a line of glasses that work to fight any existing stigmas. The gx glasses are made specifically for teens and children. The colorful and unique eyewear was made by Stefani with TURA, and some include interchangeable emojis designs.

“I am super excited to be designing kids’s eyewear! I would go shopping for glasses with my son and I saw how limited and boring the choices were. Wearing glasses should be a fun and positive experience for everyone — including kids and teens,” said Stefani in a press release.

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2.) Kevin Costner. In the wake of the 2010 BP oil spill in the Gulf of Mexico, “Waterworld” star Kevin Costner earned himself some positive headlines and became a potential hero of sorts in the cleanup process. Costner and a business partner developed a technology that could separate oil from water and significantly improve the process of oil spill cleanups. BP reportedly spent $16 million on the Ocean Therapy machines.

Unfortunately, despite excitement existing for the technology, BP and others ended up not utilizing it properly. “BP acted quickly in ordering the machines and helped us get them built … The problem is we got it out there too late,” Costner’s business partner John Houghtaling said in 2015, according to WDSU.

Related: Chaos on the Set

He continued, “In a matter of weeks this company had taken 1,400 naval architects, put Kevin’s machines on there and we were out in the Gulf. But by time we got to Gulf, they had already hit the oil with dispersants.” The technology didn’t work with dispersants. The Ocean Therapy machines require oil to be in the water in order to vacuum it away — dispersants sink the oil. Some criticized the technology for being similar to other inventions out there; they also said it did not live up to Costner’s initial promises.

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Still, the technology is apparently invaluable tool that could have the potential to stop the next oil spill from becoming as bad as that of BP’s in 2010. Costner and Houghtaling are still fighting to put the technology in front of government bodies and businesses.

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3.) Paul Newman. Many consumers buy Newman’s Own products without ever knowing that late actor Paul Newman was a co-founder of the company. Newman’s Own produces everything from salad dressing to pasta sauce to frozen pizzas. ”My profits will be divided between a number of tax deductible charities and causes, some church-related, others for conservation and ecology and things like that,” Newman told The New York Times in 1982, when he first began selling food items.

Now, Newman’s Own products support charities through the Newman’s Own Foundation. “The idea was in Paul Newman’s heart, and today, Newman’s Own, Inc. continues his commitment to pay 100 percent of net profits and royalties from the sale of our food and beverage products to Newman’s Own Foundation, a charitable organization supporting non-profits around the world,” says a statement on the company’s website.

The Newman’s Own Foundation supports a variety of causes; it helps to promote healthy eating, feeds needy families, and runs a summer camp for ill children. The best part? The food is delicious. Try the frozen pizza and the cookies.

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4.) Kevin Smith. Count “Clerks” director and podcaster Kevin Smith not as a billionaire entrepreneur — but as just another small business owner. When Smith’s films were at the height of their popularity, he opened Jay and Silent Bob’s Secret Stash in Red Bank, New Jersey — his hometown. The name was a reference to his famed characters, Jay and Silent Bob; Smith portrayed Bob.

The store is now one of the most successful comic shops in the world. At a time when digital media is taking over the reading world, Secret Stash has become a staple in its town and one of the most recognized comic book stores. Today it is the subject of the reality television series, “Comic Book Men” and involved in charity acts like blood drives and events that help support Smith’s sex slavery fighting charity, The Wayne Foundation.

The Secret Stash is run by Smith’s childhood friend Walt Flanagan and has employed others in the past, such as filmmaker Bryan Johnson and actor Jason Mewes. It is also now home to a variety of his podcasts.

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5.) Jessica Alba. The “Sin City” actress could likely comfortably retire from acting tomorrow. Alba has slowed down her film output in the last few years to dedicate her time to a business, The Honest Company, that is reportedly worth nearly $2 billion today.

The Honest Company focuses on providing clean materials, household products, and child care items that do not have harmful chemicals in them. “When I became a mom, I finally became the person I am, that I always should have been,” said Alba on the company’s website. “It’s the most satisfying job in the world. But it can also be overwhelming and confusing. I created The Honest Company to help moms and to give all children a better, safer start.”

Alba has promoted the company on various television shows such as “The Celebrity Apprentice.”

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