Theatre Brennan's graduation stage theatre performance in
A Little Silhouette of a Man, which he co-wrote and performed in with two other actors, was selected to premiere for the public at the prestigious Theatre Royal
Winchester, to a sell-out crowd. His next play,
Coffee Mornings, was produced and directed by Peter Snee and premiered at the
Stoke Repertory Theatre and the writing was described by one critic as "Pinter-esque". In 2013, Brennan wrote
Houdini. He starred in the production as Theo Houdini. The play received strong reviews. which he also produced and directed. In 2004, he wrote, directed, and produced the short film
The Blood We Cry, which aired on the BSKyB network. The film deals with a false accusation of racism and mistaken identity. In 2004, he wrote the feature film
The Lost. In 2005, Brennan wrote and produced the short film
The Fifteenth, based on the life of boxer
Howard Winstone in the 1960s. 2005 saw his first collaboration with
Horrible Histories author
Terry Deary, when Brennan was hired to adapt the best-selling trilogy of books
The Fire Thief into a feature film. In 2006, Brennan wrote the feature film
Risen, which he produced with Neil Jones, who also directed it. In 2007, Brennan was hired by Sunipa Pictures to write on spec the feature script
Life of Scars, which is yet to be produced. In 2009-10, Brennan was hired by Green Leaf Film Studios in
Chengdu, China to adapt 26 episodes of Terry Deary's
True Time Tales best-selling books for TV. The directors of the studio were so impressed with Brennan they hired him for 18 months to help set up the
VFX and
animation studio. He directed and produced the 30-minute, 3D-animated pilot episode of
True Time Tales. He also wrote a series of twelve short episodes of adaptations of classic fables, entitled
Fantastic Fables, and oversaw the production of the two-minute 2D animated pilot episode. In 2010, he wrote eight episodes of a Chinese-based
mobile phone TV series, entitled
Dynasty, for the studio. Early 2014 saw Brennan write and direct zombie thriller
Plan Z, produced by Imaginarium Tower and Zoghogg Entertainment and featuring himself,
Brooke Burfitt, and Victoria Morrison. It was released in 2016. 2015 Brennan wrote a modern adaptation of
A Christmas Carol. It was released at Christmas 2018. 2018 also saw the release of his follow-up directorial effort,
The Necromancer. == Career as a director ==