Mark O’Sullivan is a writer, director, and actor best known for his work in television. He co-created, directed, and starred in the Channel 4 comedy Lee and Dean, which aired for two seasons.

His first drama series, Tell Me Everything, produced for ITV and the BFI's Young Audiences Content Fund, addresses mental health and the challenges faced by young people today.

In 2024, Mark presented his first documentary for Channel 4 titled My Sexual Abuse: The Sitcom, which was awarded the prestigious Royal Television Society 2025 Programme Award for Art. The documentary followed Mark on his journey to explore the abuse he suffered as a child, and his attempts to make a live studio sitcom about his experiences. It received rave reviews in the UK press and media. Charities working with survivors of sexual abuse have even reported an increase in people accessing their services following the programme’s first broadcast.

Most recently, Mark launched Making Lemonade, a platform that includes a podcast, talks, workshops, and live events. Drawing from the "lemons" that Mark has experienced in his life, this initiative aims to demonstrate how creativity can transform difficult experiences into positive outcomes, effectively turning lemons into lemonade.

Before starting his career in television, Mark spent almost two decades working as a facilitator, teacher, and trainer—firstly in education, then for organisations in the public, third, and private sectors. He has designed and delivered talks, seminars, and workshops on topics from issues-based programmes like domestic abuse and hate crimes, to harnessing creativity and resilience. Mark now offers a range of talks and workshops that can be delivered 'off the shelf' or tailored to suit your organisation's specific requirements.