Suzie Costello
Suzie Costello - Torchwood Operative
Although Suzie isn't alone in having used Torchwood-acquired technology to her own advantage has - up until now - been the most destructive. Her passion to unlock the secrets of the Ressurection Gauntlet led her to commit a series of murders in the hope that she could perfect her use of the device.
Her plans went awry when discovered by P.C. Gwen Cooper, and her attempt to kill Capt. Jack was thwarted when his immortality was revealed.
Suzie took her own life and her body was stored in the Torchwood vaults as is common practice for deceased Torchwood Operatives (Torchwood:Day One).
She was revived by Gwen Cooper, using the very Ressurection Gauntlet which caused her demise when the team were investigating a series of brutal murders. They believed she held the key to a mysterious organisation known as 'Pilgrim'. It was only after they'd revived her that they began to realise she'd planned the whole affair sometime before her death (Torchwood:They Keep Killing Suzie).
Capt. Jack killed Suzie again after discovering the source of her power was through a para-physical link with Gwen Cooper, initiated by the use of the Ressurection Gauntlet. He ordered Toshiko to destroy the gauntlet, thereby severing the link.
Presently, Suzie is dead, again.