Before joining the cast of the U.S. TV series "Nip/Tuck", Julian McMahon played a powerful demon on which supernatural U.S. TV series?

Before joining the cast of the U.S. TV series "Nip/Tuck", Julian McMahon played a powerful demon on the (1998–2006) supernatural U.S. TV series "Charmed". Julian McMahon was Cole Turner/Belthazor (seasons 3–5; guest season 7). He was a half-human and half-demon who had the powers to teleport and throw projectile energy balls to stun or kill. Cole was an Assistant District Attorney sent by The Triad to kill 'The Charmed Ones'. He instead falls in love with Phoebe.

With great effort, Cole completely rids himself of his demonic nature and marries Phoebe in season four. He returns however to evil after he unwillingly becomes the new 'Source of All Evil'. As The Source, Cole is vanquished by the Halliwell sisters. He will come back from death and attempt to win Phoebe back. Cole becomes insane and is again killed by the sisters in season five. He later returns in the season seven episode "The Seven Year Witch", where it is revealed that his spirit is trapped between realms.

On "Charmed", the Halliwell sisters discover that they are descendants of a line of female witches. Each has a special ability (stopping time, moving objects, seeing the future). They can combine their abilities into the 'Power of Three' to fight demons, warlocks, dark lighters, and other evils. The sisters who are Phoebe, Piper, and Prue (Paige once Prue is gone) find out that witches with powers are part of each and every generation. The sisters do what they do since they are 'The Charmed Ones'.