Siriothrax

Siriothrax was a dragon. First mentioned in Grave Peril.

Biography
It was killed by Michael Carpenter to rescue his future wife Charity Carpenter.

Proven Guilty
In Proven Guilty, after Molly Carpenter was abducted by a Fetch, sitting in the upper pews of the balcony at Saint Mary of the Angels, Charity Carpenter told Harry the story of how Michael rescued her from Siriothrax. She had been traded to Siriothrax by Gregor in exchange for power. Charity only remembered being beaten by Gregor when she resisted and chained to an iron post by Siriothrax.