Mark O’Brien is Professor of Journalism History at Dublin City University, where his research and teaching interests focus on media and journalism history, political communication and the public sphere, crime, society and the media, and the relationship between social institutions and the media (with a particular emphasis on religion).

He is the author of The Fourth Estate: Journalism in Twentieth-Century Ireland (2017), The Irish Times: A History (2008), and De Valera, Fianna Fáil and the Irish Press: The Truth in the News? (2001). His current research focuses on the relationship between writers, journalism, and the Irish state.

He has co-edited several volumes in the areas of journalism and media history and political communication. These include The Routledge Companion to Transnational Journalism History (2026), the two volume series Periodicals and Journalism in Twentieth-Century Ireland (2014 & 2021), Political Communication in the Republic of Ireland (2014), and Political Censorship and the Democratic State (2004).

He was previously head of school at DCU, head of department at Boston University, and faculties’ administrator in the Deans’ Office at NUI Maynooth (now MU).

At DCU he chaired the MA in Political Communication in its early years and later chaired the BA Joint Honours Incorporation Panel, which unified the BA programmes of the incorporating institutions of DCU, St. Patrick’s College, and Mater Dei Institute of Education. He chaired DCU’s Media History Collection Advisory Board, the papers of which have now been incorporated into the University Library’s Special Collections Unit. He is currently chair of the Mary Raftery Prize for Journalism.