From The TimeSplitters Wiki

The Ringmistress is a character in Timesplitters 2. You take control of her in most of the arcade challenges involving the circus (which she runs). She is one of the hardest characters to unlock as you need a gold medal on the Bags Of Fun challenge, so not many players have her unlocked. She also is noticable for in a Virus or Flame Tag match, when caught, she does a loud and long scream, that is shared with no other characters.