In The Chronicles of Narnia by C.S. Lewis, Caspian was the name of a series of Kings of Narnia. The most prominent of them was Capsian X. Caspian X was orphaned as a small child and was raised by his uncle, Miraz. Miraz had murdered Caspian's father. When Caspian was a teenager, Miraz had his own son. Caspian's tutor urged him to flee on the night of the child's birth, believing that Miraz would kill Caspian to pave the way for his own son to rule. He encountered the Pevensies, who had returned to Narnia, and Aslan. After the Pevensies returned to their own world, Caspian was made King of Narnia.
In Highlander: The Series, Caspian was an immortal. He was born around 1300 B.C. and was a member of the Four Horsemen, a group of vicious raiders who were active during the Bronze Age. By the 20th century, Caspian had become a serial killer. He was in an insane asylum in Romania until one of the other Four Horsemen broke him out. Caspian was killed when he and another horseman dueled with MacLeod.
Caspian comes from the name of the Caspian Sea, which is derived from the name of the city Qazvin, which in turn takes it's name from the ancient Cas tribe. In 2014, 87 boys were named Caspian in the U.S.