Sam Mendes started in theater, saying "exit, stage right" to stars like Judi Dench, Julianne Moore, and Nicole Kidman. Well-known in the theater world, Mendes made a big splash in Hollywood with American Beauty, the 1999 Best Picture winner that had people going gaga over plastic bags.
Having won an Oscar for American Beauty, Mendes continued directing films, plays, and marrying and divorcing Kate Winslet, until he took over the Bond franchise with Skyfall.
While the director of family dramas like American Beauty and Revolutionary Road might seem like a weird fit for the Bond franchise, Mendes thought it was a perfect match. "This Bond is about a middle-aged Brit, made by a middle-aged Brit," he told The Guardian in 2012 (source).
Mendes stuck with Bond to make Spectre in 2015, making him the first director since John Glen to direct two Bond flicks in a row. After Spectre, Mendes hasn't been attached to another Bond film. But in the words of Bond himself, never say never again.