Spencer Kornhaber in The Atlantic:
In 1949, the legend goes, B.B. King ran into a burning building to save a guitar he loved. The dance hall he’d been playing at in Twist, Arkansas, caught flame when two men knocked over a barrel of fuel while fighting about a woman. The woman’s name was Lucille—and from that point on, King’s guitar was named Lucille, too. Though Gibson would later launch a B.B. King Lucille model, and King indeed favored that company’s instruments, there wasn’t just one Lucille. Most any guitar he’d play would get the name. Much like how the name came to stand in for the instrument, King’s name came to stand, in the public’s imagination, for the kind of music he played. When people today talk about the blues, they’re talking in part about B.B. King; when they talk about B.B. King, they’re talking about the blues. The two concepts are the same.
More here. (Note: I had the honor of hearing him live many times. With his passage, an entire era has ended.)