At 91, Tony Bennett is not just the dean of crooners, he’s the king of duets. Bennett, who began his career shortly after fighting in Europe during the final year of World War II, spent much of his first 40 years in the recording industry being called the “heir apparent” to Frank Sinatra among jazzy pop singers.

And, like Sinatra with his Rat Pack, he often sat in with other singers and sang duets. Bennett's vocal partners in the 1950s and '60s ranged from Judy Garland to Andy Williams. After a career downturn in the 1970s, Bennett rebounded with a series of collaborations with contemporary artists, orchestrated by his manager son, Danny Bennett.