TOB Architect is an explorative, critical architectural practice based in Dublin, Ireland. It was founded by Thomas O Brien in 2013 and since then has earned a reputation as an expansive practice that incorporates an ongoing examination of the nature of things and places into each project. The practice is a registered RIAI practice with Conservation Grade 3 accreditation.

The practice is particularly interested in rural contexts and the distinct culture that sets the rural way of seeing apart from the urban. The practice is critical of some accepted ideas of the vernacular and typology, and finds more fruitful soil for creative practice in the differing logical approaches and systems that inform rural culture, such as a more ad-hoc approach to building, and a more complex concept of the relationships between humans, objects, land and animals.

The practice has been recognised domestically and internationally, receiving an Architectural Association Award 2019 for Killan Farmhouse, and being shortlisted for the international Architectural Review Emerging Architect prize in 2018. A continuing level of excellence in the built work of the practice is recognised by worldwide publication in printed and online media. The practice received an Arts Council Bursary in 2017 and in 2020. Work by T O B Architect has been exhibited to the public at PADA studios, Lisbon - April 2021, The Irish architecture Foundation , Dublin , June/September 2021, and the Royal Hibernian Academy, Annual Show - September/October 2021.

Thomas is a Design Fellow at University College Dublin where he teaches in the first year and fifth year studios.