Brian Anthony Brennan is a Canadian journalist, broadcaster, musician, and writer who specializes in books about the colourful personalities of Western Canada's past. He was born 4 October 1943 in Dublin, Ireland, immigrated to Canada in 1966 and has lived in Calgary, Alberta since 1974. He spent 25 years as a staff writer with the Calgary Herald, from 1974 to 1999 writing columns and feature stories, and reviews on theatre, the police beat, tributes, and the 1988 Olympic Arts Festival. He was a full time staff writer for the Herald's Sunday Magazine between 1988 and 1991 when it ceased publication. Before moving to Alberta in 1974, he worked for the Smithers Interior News (1968-1970) and wrote about politics for Southam News in Ottawa (1973-1974). He also wrote for the New York Times, the Toronto Star and starting in the late 1990s for the Globe and Mail (obituaries).

Brennan was a leader in the attempt by the Communications, Energy and Paperworkers Union of Canada to organize a union local and negotiate a first contract with the Calgary Herald. Before and during the eight-month strike by journalists in 1999 and 2000, Brennan was a member of the union's bargaining committee. When the strike ended in June 2000 with the dissolution of the union, he left the Calgary Herald to devote himself full-time to writing books and magazine articles including for Galleries West Magazine.

He wrote the following books: Máire Bhuí Ní Laoire: A Poet of Her People. Cork, Ireland: The Collins Press, 2000. Building a Province: 60 Alberta Lives. Calgary: Fifth House, 2000. Alberta Originals: Stories of Albertans Who Made a Difference. Calgary: Fifth House, 2001. Scoundrels and Scallywags: Characters from Alberta's Past. Calgary: Fifth House, 2002. Boondoggles, Bonanzas, and Other Alberta Stories. Calgary: Fifth House, 2003. Romancing the Rockies. Calgary: Fifth House, 2005. How the West was Written: The Life and Times of James H. Gray. Calgary: Fifth House, 2006. Songs of an Irish Poet: The Mary O'Leary Story. Calgary: Bowness Press, 2007. The Good Steward: The Ernest C. Manning Story. Calgary: Fifth House/Fitzhenry & Whiteside, 2008. Leaving Dublin: Writing My Way from Ireland to Canada. Calgary: RMB | Rocky Mountain Books, 2011. The Calgary Public Library: Inspiring Life Stories Since 1912. Calgary: Kingsley Publishing, 2012. Rogues and Rebels: Unforgettable Characters from Canada's West. Regina: University of Regina Press, 2015.

As a storyteller, Brennan appeared regularly on the CBC Radio program Daybreak Alberta.

Brennan was short-listed for the 2003 Grant MacEwan Author's Award, nominated for the Irish Times Literature Prize, 2001, and has received two Western Magazine Awards and the national Hollobon Award for journalism. He was the first winner of the Dave Greber Freelance Writers Award, presented in 2004.