Pa'u Zotoh Zhaan

Zhaan is a Delvan, a blue, humanoid plant-species, and a priestess. She murdered her lover who was collaborating with the corrupt Peacekeepers against the Delvans, and was imprisoned aboard Moya.

Zhaan has several empathic and telepathic abilities, plus the ability to make explosives and drugs in her workshop. While willing to defend herself and others, she was generally reluctant to employ violence. However, she had no qualms about cutting off one of Pilot's arms or vamping Rygel to accomplish her goals.

Warning: Wikipedia contains spoilers

Zhaan made herself critically ill to save the near-death Aeryn Sun. While searching for a planet with the right conditions for Zhaan to root and heal, Moya collided with another spacecraft. In order to save Moya and her crew, Zhaan sacrificed herself by piloting the other craft away before it was destroyed.

Virginia Hey left the show early in the third season because the character's extensive makeup was affecting the health of her kidneys. She did make return appearances in two fourth season episodes, wearing the makeup.