Mylan Pharmaceuticals, a global pharmaceutical company until 2021, was founded in West Virginia. Mylan operated a major manufacturing facility in Morgantown, one of the company's 39 sites around the world.

Mylan produced approximately 1,400 generic pharmaceuticals and several brand medications to treat diseases such as arthritis, depression, diabetes, Parkinson's disease, and schizophrenia. In addition, it offered a range of drugs to nearly 40 percent of HIV/AIDS patients in developing countries.

Mylan was founded in 1961 as a pharmaceuticals distributor by Milan "Mike" Puskar and Don Panoz in White Sulphur Springs, opening in a former skating rink. The company initially purchased finished goods from other companies and resold them to pharmacies and doctors across rural parts of the state.

The distribution company began making vitamins and antibiotics when it moved to Morgantown in 1965. In 1966, Mylan manufactured a generic version of penicillin G, which launched its success. The company boomed in the 1980s, when Congress made it easier to receive Food and Drug Administration approval for generic drugs.

In 2014, Mylan acquired some of Abbott Laboratories' non-U.S. businesses, and subsequently moved its tax address to the Netherlands where lower corporate tax rates are in place. The company was criticized for the move. In 2019, Mylan merged with Pfizer's Upjohn division, creating a new company, Viatris Inc., which became the owner of Mylan Pharmaceuticals. In December 2020, Viatris announced that the Mylan plant in Morgantown would cease manufacturing on July 31, 2021, eliminating almost 1,500 jobs in the area. Closure activities are to continue until March 31, 2022.

Mylan was one of the largest active pharmaceutical ingredient manufacturers, at one time marketing products in 145 countries and territories. In the United States, one in every 13 prescriptions dispensed, brand or generic, was filled with a Mylan product.