Cassius Warrington was born in either 1977 or 1978 and came to be educated at Hogwarts School of Witchcraft and Wizardry in 1989. The Sorting Hat placed him in Slytherin House during the Sorting ceremony and his Head of House was Professor Severus Snape, the Potions master.
1993–1994 school year
In 1993, Warrington replaced Adrian Pucey as Chaser on the Slytherin Quidditch team with Marcus Flint as the Quidditch Captain. Lee Jordan, the Commentator at the time, said that Flint was "going for size rather than skill" in the lineup in reference to Warrington. On the last day of the season, Slytherin lost to the Gryffindor Quidditch team during the re-scheduled match, and thus Gryffindor won the Quidditch Cup. Also that same year, Warrington presumably sat his O.W.L.s under the Wizarding Examinations Authority.
1994–1995 school year
In 1994, Quidditch was cancelled due to the Triwizard Tournament being held in Hogwarts. When Albus Dumbledore placed the Goblet of Fire in the Great Hall in order for students to try to compete, it was rumoured that Warrington put his name in. If so, it was for naught, as Cedric Diggory was chosen over him.
1995–1996 school year
During this school year, Warrington played Quidditch on the Slytherin team against Gryffindor and scored against the new Gryffindor keeper, Ron Weasley, who was still trying to get his confidence. This same year, Dolores Umbridge became the Defence Against the Dark Arts Professor and later High Inquisitor of Hogwarts. As High Inquisitor, Umbridge formed the Inquisitorial Squad, of which Warrington was a member, who were given the power to dock House points from all students, including Prefects. The squad had a hard time keeping order though, as many of them came down with weird ailments. Warrington, for instance, reported to the hospital wing with a horrible skin complaint that made him look as though he had been coated in cornflakes. When Harry Potter tried to contact Sirius Black, he had several students create diversions. Warrington and several others tried to catch students, and Warrington caught Ginny Weasley and Neville Longbottom. At the end of the year, Umbridge left and the Squad was disbanded.
Warrington presumably sat his N.E.W.T.s and graduated from Hogwarts this year.
- Harry Potter and the Prisoner of Azkaban (First appearance)
- Harry Potter and the Goblet of Fire
- Harry Potter and the Order of the Phoenix
- Harry Potter and the Order of the Phoenix (film) (First identified as Cassius Warrington on film prop in Harry Potter Wizard's Collection)
- Quidditch Through the Ages (Mentioned only)