Callen Martin

About Callen

Callen Martin is a literary agent at Madeleine Milburn, where he joined in January 2026 from Bell Lomax Moreton. He focuses on accessible Middle Grade (7+), YA and SFF fiction with an action and adventure focus. Callen graduated from Bath Spa University's MA in Writing for Young People in 2019. He began his publishing career with internships and work experience at Chicken House, Walker Books and Penguin Michael Joseph, and has worked freelance as a publisher's submission reader, writing competition judge, sensitivity reader and manuscript assessor. In 2026 he was confirmed as the agent judge for the titular prize of the Times / Chicken House Children's Fiction Competition.

What Callen is looking for

Callen is looking for Middle Grade (7+), YA, New Adult and SFF fiction in all genres and formats, though not verse, poetry or picture books. In YA he is drawn to high concepts, a strong sense of voice and clear emotional depth. In SFF he is looking for magic systems and worldbuilding that are unique but accessible.

Submissions

At the time of checking (November 2026), all of the agency's agents were open to submissions, and Callen is listed as an option on the Children's and YA submissions form. Send Children's and YA work only once the manuscript is complete, with a one-page synopsis and the first three chapters or first 10,000 words in a single document. Submissions must go through the website forms, as other routes are not considered, and the agency takes up to 12 weeks to consider a manuscript. AI-generated material is not accepted.

Compiled from Madeleine Milburn Literary, TV and Film Agency's own website. Check there for the latest before you submit.

View full profile at Madeleine Milburn Literary, TV and Film Agency

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