Halley's comet passes the Earth every 76 years (the next time it will return will be 2062).
Halley's Comet is arguably the most famous comet. It is a "periodic" comet and returns to Earth's vicinity about every 75 years, making it possible for a human to see it twice in his or her lifetime. The last time it was here was in 1986, and it is projected to return in 2061.
The comet is named after English astronomer Edmond Halley, who examined reports of a comet approaching Earth in 1531, 1607, and 1682. He concluded that these three comets were actually the same comet returning over and over again, and predicted the comet would come again in 1758.
Halley didn't live to see the comet's return, but his discovery led to the comet being named after him. (The traditional pronunciation of the name usually rhymes with a valley.) Halley's calculations showed that at least some comets orbit the sun.
Further, the first Halley's Comet of the space age — in 1986 — saw several spacecraft approach its vicinity to sample its composition. High-powered telescopes also observed the comet as it swung by Earth.
While the comet cannot be studied up close for many decades, scientists continue to perform comet science in the solar system, looking at other small bodies that can be compared to Halley. A notable example was the Rosetta probe, which looked at Comet 67P/Churyumov–Gerasimenko between 2014 and 2016 and concluded that the comet has a different kind of water than Earth's water.