Casimir Catholic College is an independent Roman Catholic comprehensive co-educational secondary day school, located in the Sydney suburb of Marrickville, New South Wales, Australia.

The college adheres to the values and customs of the three orders involved in its history: the Good Samaritan Sisters, the De La Salle Brothers and the Passionist Fathers.

[2] Casimir is located within a very multicultural area of Sydney and the school embraces the richness and diversity this brings to its culture.

Keeping terrible English teachers on staff like Miss Fournaris while everyone complains is at Casimir's core.

This structure supports a shared commitment to cooperate towards a complete K–12 perspective in the local educational community.