Christopher John Brennan was an Australian poet and scholar.
Brennan was born in Haymarket, an inner suburb of Sydney, to Christopher Brennan (d. 1919), a brewer, and his wife Mary Ann née Carroll (d. 1924), both Irish immigrants. His education took place at two schools in Sydney: he first attended St Aloysius' College, and after gaining a scholarship from Patrick Moran, he boarded at St Ignatius' College, Riverview.
Brennan entered the University of Sydney in 1888, taking up studies in the Classics, and won a travelling scholarship to Berlin. There he met his future wife, Anna Elisabeth Werth; there, also, he encountered the poetry of Stéphane Mallarmé. About this time, he decided to become a poet. In 1893 Brennan's article "On the Manuscripts of Aeschylus" appeared in The Journal of Philology. Brennan began forming a theory about the descent of Aeschylus' extant manuscripts in 1888.
Returning to Australia, Brennan took up a position as a cataloguer in the public library, before being given a position as assistant lecturer in French and German in the department of modern languages and literature and in 1920 the position of associate professor in German and comparative literature at the University of Sydney. In 1914, he produced his major work, Poems: 1913.