Christopher John Brennan (1 November 1870 – 5 October 1932) was an Australian poet and scholar.
Brennan was born in Sydney, to Christopher Brennan (d.1919), a brewer, and his wife Mary Ann (d.1924), née Carroll, 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 at the University of Sydney. In 1914, he produced his major work, Poems: 1913. After Brennan's marriage broke up in 1922, he went to live with Violet Singer, the 'Vie' of his later poems, and, as a result of both his divorce and increasing drunkenness, he was removed from his position at the University in June 1925. The death of Violet Singer in an accident left him distraught, and he spent most of his remaining years in poverty. Brennan died in 1932, after developing cancer.
Brennan was not a lyric poet. It was not emotion that drove his work, rather, it displays at its best an architectural, and mythological resonance that informs it. His chief work was designed to be read as a single poem, complete, yet formed of smaller works. It covers not only the basic details of his life, such as his wooing of his wife in the early portions, but also human profundities through mythology, as in the central Lilith section, and the Wanderer sequence. As such, it is among the most widely discussed works of Australian poetry, judging from the prominence of criticism about it and Brennan.
Brennan belonged to no particular group in Australian literature. Neither a balladist, nor a member of the emergent "Vision" school, his closest affinities are with the generation of the 1890s, such as Victor Daley. This is not surprising since the bulk of his work was produced during this period. However his importance in Australian letters rests upon the seriousness he approached his task as a poet and his influence upon some later poets, such as Vincent Buckley.
Brennan influenced Australian writers of his own generation and many who succeeded him, including R. D. Fitzgerald, A. D. Hope, Judith Wright and James McAuley. In remembrance, the Fellowship of Australian Writers established the Christopher Brennan Award which is presented annually to an Australian poet, recognising a lifetime achievement in poetry.
Brennan Hall and Library at St John's College within the University of Sydney, the Christopher Brennan building in the University's Arts Faculty, and the main library at Saint Ignatius' College, Riverview are named in his honour.
- Sir Roger de Coverley, Selections from The Spectator (Sydney : Turner and Henderson, 1892). Edited with: A. B. Piddington.
- XVIII Poems: Being the First Collection of Verse and Prose (Sydney : privately stylographed, 1897).
- XXI Poems: MDCCCXCIII-MDCCCXCVII: Towards the Source (Sydney : Angus and Robertson, 1897).
- Fact and Idea (Sydney : Govt. Printer, 1899).
- From Blake to Arnold: Selections from English Poetry, 1783–1853 (London : Macmillan, 1900). Edited with: J. P. Pickburn & J. Le Gay Brereton.
- A Mask (Sydney : Sydney U. Women's College, 1913). With: J. Le Gay Brereton.
- Poems (Sydney : G. B. Philip and Son, 1914).
- Passages for Translation into French and German (London : Oxford University Press, 1914). Compiled with: G. G. Nicholson.
- A Chant of Doom: and Other Verses (Sydney : Angus and Robertson, 1918).
- Twenty Three Poems (Sydney : Australian Limited Editions Society, 1938).
- The Burden of Tyre (Sydney : Harry F. Chaplin, 1953).
- The Verse of Christopher Brennan ed. by A. R. Chisholm and J. J. Quinn (Sydney : Angus and Robertson, 1960).
- The Prose of Christopher Brennan ed. by A. R. Chisholm and J. J. Quinn (Sydney : Angus and Robertson, 1962).
- Selected Poems of Christopher Brennan (Sydney : Angus and Robertson, 1965). Ed. by: A. R. Chisholm.
- Selected Poems of Christopher Brennan (Sydney : Angus and Robertson, 1973). Ed. by: G. A. Wilkes.
- Prose-Verse-Poster-Algebraic-Symbolico-Riddle Musicopoematographoscope & Pocket Musicopoematographoscope (Erskineville, NSW : Hale and Iremonger, 1981). Ed. by: Axel Clark.
- Christopher Brennan ed. by Terry Sturm (St. Lucia, Qld : U. of Queensland Press, 1984).
- 13 Poems (Pearl Beach, NSW : Escutcheon Press, 1987). Ed. by: R. E. Summers.
- Interludes: Six Poems (Pearl Beach, NSW : Escutcheon Press, 1991).
- Christopher Brennan: Introduction suivie de 12 poèmes – textes et traductions – avec commentaires ([S.l.] : L'Harmattan, 2005). Ed. and trans.: Simone Kadi.
- The Autumnal Glory of Valvins: Christopher Brennan on Mallarmé (Banora Point : Wind and Wave Press, 2007). Ed. by: Phillip A. Ellis.
- Like a Dream of Stone: Selected Verse Translations by Christopher Brennan (Banora Point : Wind and Wave Press, 2007). Ed. by: Phillip A. Ellis.
- The AustLit page on Brennan
- Australian Authors – Christopher Brennan
- The Australian Dictionary of Biography entry on Brennan
- The Australian Poetry Library entry on Brennan contains 86 poems by Brennan.
- Australian Studies Resources contains texts of Brennan's poems in pdf format.
- "Life as Whitest Flame" is a Sydney University article on Brennan by Christopher Bowen.