Earth

Earth, also known as Terra in Inspector #13, is the home planet of Humans (and some human/alien hybrids) and many animal life forms, located in the Solar System. Earth is said to be a Level 2 planet and it appears as the common setting in many Ben 10 episodes. An odd thing about the planet is that a great deal of alien activity happens on earth which isn't a trans-galactic level civilization. This has led to the majority of the plot lines within the Ben 10 series, as well as a major story arc within Ben 10: Alien Force.

Ben 10: Ultimate Alien Cosmic Destruction
It is the main setting of the game where the Potis Altiare was sent by the Galvan when it crashed on earth many years ago.

Possible Future
The Earth begins to have a substantial ethnicity diverse population of aliens sometime between Ben being 15 and 30.

Another alternate future of the Earth was seen in Paradox, when Professor Paradox showed Ben and the gang what will happen if the time-warping creature gets out of Los Soledad and wanders off in the whole world with the Earth looking like a deserted wasteland.

Ben 10-Generator Rex: Heroes United
A parallel version of earth exist where E.V.O.s and Providence existed and nearly every living being is infected by nanites.

Trivia

 * Earth is the richest source of Iron in the universe.
 * 4 of Earth's native species DNA is in the Codon Stream including Human and Dolphin DNA.