Co-COO, Walgreens Boots Alliance, 64
As co-COO of the $118.2 billion pharmacy chain Walgreens Boots Alliance, Barra’s responsibilities are considerable. Based in London—though she makes frequent trips to the U.S. where WBA is headquartered—the veteran executive runs global purchasing (WBA is now the world’s largest purchaser of generic drugs) and supply chain as well as central functions like HR. The wholesale business that she manages involves a network of 390 distribution centers and 230,000 pharmacies. She also leads retail pharmacy outside of the U.S. and the U.K., which means she oversees stores—not to mention their online businesses—in 13 countries as well as an investment in the major Chinese drug store chain GuoDa. The multi-faceted role is one fitting for Barra, a trained pharmacist, who began her career in the business decades ago by opening her own pharmacy in her Italian hometown.