Dylan ap Rhys Wiliam[3] is a Welsh educationalist.

He lives in Bradford County, Florida, United States.

[4][5] Born in North Wales, Wiliam grew up in a monoglot Welsh-speaking family.

[9] Wiliam, along with Black were educational advisors to Tony Blair, and in 2013 Wiliam and Black wrote a report that criticised the current assessment, stating "A-level grades are an unreliable guide to a student's ability.

"[10] He demonstrated his ideas in a 2010 BBC documentary series, The Classroom Experiment, in which a class at Hertswood School was encouraged to participate more widely in activities such as answering questions.