Halley's Comet is the best-known of the short-period comets and is visible from Earth every 75–76 years. It's the only naked-eye comet that might appear twice in a human lifetime. Other naked-eye comets may be brighter and more spectacular, but will appear only once in thousands of years.
In 1705 astronomer Edmond Halley (1656-1742) predicted, using Newton's newly formulated laws of motion, that the comet seen in 1531, 1607, and 1682 would return in 1758 (which was, alas, after his death). The comet did indeed return as predicted and was later named in his honor.
Halley's comet appeared in 1986 and will next appear in 2061.