NEW YORK—Actor Michael K. Williams, who as the rogue robber of drug dealers Omar Little on “The Wire” created one of the most popular characters in television in recent decades, died Monday. Williams was found dead Monday afternoon by family members in his Brooklyn penthouse apartment, New York City police said. He was 54. His death was being investigated as a possible drug overdose, the NYPD said. The medical examiner was investigating the cause of death. Little, a “stick-up boy” based on real figures from Baltimore, was probably the most beloved character among the devoted fans of “The Wire,” the HBO show that ran from 2002 to 2008 and is re-watched constantly in streaming. The Brooklyn-born Williams was also a ubiquitous character actor in other shows and films for more than two decades, including roles on the HBO series “Boardwalk Empire” and “Lovecraft Country,” and in the films “12 Years …