1. Pioneer 11: Flew by Saturn in 1979, taking the first close-up images of the planet and its rings.

2. Voyager 1: Flew by Saturn in 1980, providing more detailed images of the planet and its moons.

3. Voyager 2: Flew by Saturn in 1981, focusing on the planet's atmosphere and magnetic field.

4. Cassini: Orbited Saturn from 2004 to 2017, providing an incredible amount of data about the planet, its rings, and its moons.

It's important to note that while these are the only probes to visit Saturn, there have been other missions that have observed the planet from afar, such as the Hubble Space Telescope.