The great majority of the largest companies in America are easily identified by name by most consumers. That is because their names match one or more of their most important brands. McDonald’s in the fast food business. It is its own largest brand. The same is true for companies including Ford, or Google, or AT&T.

But there are a number of huge companies, many with revenue in the tens of billions of dollars, many with revenue greater than firms with famous brands, that are almost completely unknown to the public. Investors often do not know the names of these firms and very few know what businesses they are in.

A small number of large companies do not care if the consumer knows their name or what they do. Some make or distribute brand-name products and make massive sums of money doing it. Others supply parts and services to companies that do have major brands. Obscurity does not directly relate to sales, as the companies on this list show.

Among the companies on this list are Altria, which manufactures and distributes Marlboro cigarettes, one of the best know brands in the world. Also on the list is TJX which owns the Marshals department store chain, and Aramark which supplies over one million meals to people in the nation’s prisons.