Ramirez says it best.
From the Dawn of time We came; moving silently down through the centuries, living many secret lives, struggling to reach the time of the Gathering; when the few who remain will battle to the last.

Highlander The Series?

A spin off from the Highlander films starring Christopher Lambert, The Series is about Duncan MacLeod, born in 1592 in the Highlands of Scotland. It lasted six seasons Duncan  is played by

Adrian Paul also starring Stan Kirsch,
Peter Wingfield, Jim Byrnes,  Alexander Vandernoot, and Elizabeth Grason.

The Quickening?
An Immortal can only be killed by beheading. When an Immortal is killed, the Immortal who killed him receives his power and his essence and his knowledge
known as the Quckening.

The Gathering?

Only a few of us are left, we will feel an irresistible pull towards a far away land.