Geraldine Diamond

COLT-5000 was a bounty hunter hired to find Jenny for her valuable Time Lord biodata.

Arriving at the Vesh Taralesh Emporium, she killed Vesh Taralesh when she refused to divulge information on Jenny's location. She made a deal with Garundel so that she could track Jenny across time and space, as long as she spared Garundel's life, and was intrigued by his information on Noah. (AUDIO: Stolen Goods)

COLT-5000 later tracked Jenny to Kamshassa, being given information by offering a reward. The newly liberated people held her off long enough for Jenny and Noah to escape. (AUDIO: Neon Reign)

She caught up with them in zero space at the Eye of the Storm. She forced the clone scientists aboard to help her capture them by exploiting their superstition that the death of the original scientists they were based on would kill them and also planted a wormhole bomb. She caught Jenny and Noah and had them taken to the station’s cloning facilities, planning to clone them to sell their DNA multiple times. Jenny persuaded the clones to turn on her, prompting her to detonate the bomb. She attempted to break-in to Jenny and Noah’s ship, the Jenny One, as they prepared to enter the wormhole to close it behind them to save the clones. They successfully flew into it, with the COLT-5000 being lost in the process. (AUDIO: Zero Space)

Behind the scenes
According to Sean Biggerstaff, Barnaby Edwards "went straight to Dame Siân Phillips" to cast COLT-5000. Before this casting was annouced, the cover for Jenny: The Doctor's Daughter showed COLT-5000 with a male actor.