What connections did Michelangelo have to other renaissance figures of their time?

Leonardo was employed (some of them for a brief time, some of them for a long time) by the following:

Lorenzo de' Medici

Ludovico Sforza, Duke of Milan

Cesare Borgia

Cardinal Giulio de' Medici (Cousin to Pope Leo X and who later became Pope Clement VII)

Francois I, King of France