Aliens? Who knows...but her is a list of the characteristics of five alien species that have captured the imaginations of Earthlings.

1. The Greys

The Greys have greyish-dark, blue skin looks with long arms, legs and fingers. This is the most common type of aliens you see in the movies They have big heads, big eyes that look similar to insects and no visible pupil. The Greys never talk as they communicate using mental-telepathy. Finally, they Greys are about 3-5 feet tall.

2. The Leader Greys

This type of alien is also similar to The Greys in appearance, but the Leader Greys are much taller than The Grey, up to 7 feet tall. The Leader Greys are usually not associated with operation or studies of humans, they usually watch and instruct the Greys, no wonder they are called the Leader Greys.

3. The Reptiles

The Reptiles are the most dangerous type of aliens. Similar to the Leader Greys, they are around 7 feet tall, with large teeth, claws and often covered in scales. These aliens are very vicious and dangerous! You will want to avoid any encounters with them.

4. The Nordics

The Nordics are considered as the most civil types of aliens. They have blond hair and look a lot like humans in every way. This type of alien is peaceful, highly evolved and can easily communicate with humans. The Nordics are not on good terms with the Greys and Reptiles because they know that these aliens are trying to hurt the human race; this is why the Nordics are very helpful to humans.

5. Bigfoots and the Robots

These two types of aliens can sometimes be very dangerous to humans, except for their females that have been said to help some humans in some cases. The Bigfoots and the Robots usually work for the Grey by carrying their supplies everywhere. Unlike the Bigfoots that just work for the Greys, the Robots will kill humans on sight because they are not very visual in their ability to identify what you are. They will bring your body to the Greys for examination, and then create a clone of your DNA and use it to spy human on earth. The bottom line is that, as much as possible avoid both Bigfoots and Robots.

Find out more by visiting the 'Alien Watchers' website below.