Stella Knight is the Chief Agent of MI9.
She can be strict, but cares for the agents and doesn't want them to get hurt. If the mission goes wrong, she usually holds herself responsible, showing her more maternal side. She follows protocol no matter what; in Trojan KORPS she arrested Frank for being a traitor, even though her feelings said otherwise, because all the evidence pointed to him.
She used to be Frank's girlfriend 10 years ago, until she dumped him. In The Fall of SKUL, it is shown that they are still close although tensions arise between them during the course of the series. It is revealed that the the source of this conflict is when Frank led the final assault on the KORPS base. The MI9 team suffered terrible losses and Stella blamed Frank for the disaster. She realizes it wasn't Frank's fault and in, The Final Endgame, she risks her life to help him. Then they both kiss just before almost dying. After they are saved Stella asks if they can forget about it to which Frank says he doesn't think they can.
In League of the Mata Hari, she was removed from command and arrested. In We Need to Talk About KORTEX, she was saved from prison by the team and helps them take down KORPS, bringing down Mike Stern and Hamish Campbell. It is unknown if she was reinstated after this.
- Free Runner is her only appearance at St Hearts outside of the MI High base.