Alti

Alti is an evil shamaness whom Xena befriended in her bad old days and who promised to make Xena "Destroyer of Nations".

Whilst searching for Gabrielle, Xena discovers that Alti is preventing dead Amazons from passing through the gate into the afterlife and, feeling remorse for causing the deaths of these Northern Amazons (notably Cyane) she vows to help them against Alti. This makes Alti her enemy, of course, and Alti shows Xena a vision of the future (Xena and Gabrielle crucified together). Xena's hope is now renewed as she knows Gabrielle must still be alive and this renews her strength and resolve, enabling her to kill Alti. However, Alti returns and Xena has to destroy her all over again.

Despite being trapped in the spirit world, Alti makes a final bid to return to the material realm by stealing the soul of Xena's unborn child so she will be born instead. After Gabrielle is nearly killed in the spirit world, Xena travels there herself and tricks Alti into thinking she has won. A battle ensues between the two and Alti's spirit is destroyed.

This wasn't the end for the evil shamaness though. She reappeared in the modern world disguised as Dr. Alexis, the genetics expert. With her knowledge, she brings clones of Xena and Gabrielle into the world and, no she isn't doing this out of a sense of remorse or guilt! She programs the Xena clone with images of Xena's evil past, omitting all memories of Gabrielle. Alti/Alexis then gets Gabrielle arrested so Xena goes on the rampage. This all ends with Xena and Alti fighting it out but, of course, Xena wins and Alti is destroyed yet again.

Julius Caesar messes with the Fates' loom and creates an alternative world, where Alti is High Priestess of Rome and he and Xena are Emperor and Empress. Alti plans to dispose of Xena and make herself Empress in her place. Sure enough, she soon has Caesar promising to make her Empress. However, whilst in bed with him, she stabs him to death. This time it looks like Alti will win but she is once again destroyed when Gabrielle sets fire to the Fates' loom.