Mars.
April 2008 At present the only planet in our solar system that has not been visited (either by an orbiting spacecraft or flyby spacecraft) has been the recently planet downgraded body of Pluto. There is a mission currently in motion to visit this distant outpost.
All of the eight planets have been visited or orbited by space probes.
there has been 16 probes that had been sent to venus.
If by humans visiting you mean , Which planet's have had humans land on that planet the answer is none. The only other place in space that humans have visited is the moon.
At current we have sent, or are sending, probes to all of the planets in our solar system. The probe Voyager has visited several planets, including Jupiter and Neptune, while Cassini is currently in orbit around Saturn.
no
Space Probes.
Chicken
Yes, NASA has sent a couple of unmanned probes to examine Mercury, Mariner 10 which did a flyby and the MESSENGER orbiter.
One space probe has been sent to Pluto: NASA's New Horizons spacecraft. It performed a flyby of Pluto in July 2015, providing the first close-up images and scientific data of the dwarf planet and its moons.
The U.S. has sent a number of space probes to the planet Mars. Several have been orbiting camera platforms, while others have been rovers or lander.
aside from earth, the planet that has been visisted by the most probes, is often said to be mars, however other scientific research has also proven that venus and Jupiter had also been visisted by several probes every 200 - 400 years. mars however is often visited by probes every 50 - 100 years.