X-1Z (aka "X")

Only sighted 2 times on Earth.

According to reports from other races they are able to shape-shift as many as 4 times in 10 seconds.

Their origin is unknown.

They conduct Human abductions and perform medical experiments on the subjects.

They have been visiting Earth since the mid-1500's.

The only 2 confirmed sightings happened near Elazig, Turkey.