In other words, an introduced species that has a tendency to spread and is able to cause damage to the environment, the human economy, and human health. Some of these invasive creatures have caused the extinction of the whole entire species and have irreparable damage to a surrounding ecosystem. With that said, don’t be fooled into thinking that these creatures are scary or even dangerous looking. Some of these creatures were actually kept as pets because they are so cute or even exotic. However, the sad reality is that when introduced into an environment where natural predators where not present, these animals got out of control and completely took over their respective areas. From the adorable looking gray squirrel to the frightening Burmese Python these are 25 Most Invasive Creatures On Earth. If you want to see animals who are destructively dangerous, check out the 25 most dangerous animals in the world.