Caleb was born in 1648 in the Bay colony of Massachusetts, he was a foundling who was raised by a puritan family who taught him that self-reliance was a virtue, that it was better to strike out on your own, a lesson Caleb took to heart. In 1687, Caleb died when a tree fell on him and crushed him while he was chopping wood and became Immortal.

He soon learned the ways of the Immortals from Goodman Fletcher. Some years later, Caleb killed fellow Immortal Carl the Hermit, who had taught Duncan MacLeod how to track and survive in the wilderness. Cole, too, would learn all of Carl's knowledge.

Caleb is well versed in various weapons and fighting styles. He carries a rifle and pistol on him and when dueling with immortals uses a custom battle axe.