James William Acaster (born 9 January, 1985) is an English comedian originally from Kettering, Northamptonshire, who now lives in London.

He has performed for several consecutive years at the Edinburgh Festival Fringe and has been nominated for Best Show five times. He won the Melbourne International Comedy Festival Award for Most Outstanding Show in 2019 with Cold Lasagne Hate Myself 1999, and has won four Chortle awards.

Acaster has appeared on several panel shows, including Mock the Week, Taskmaster, 8 out of 10 Cats, and Would I Lie to You?. He has a 2018 Netflix show titled Repertoire, consisting of four, hour-long stand-up comedy performances. He has also written two Sunday Times Best-Selling books, James Acaster’s Classic Scrapes, consisting of true stories, most of which were originally told on Josh Widdicombe’s show on XFM, and Perfect Sound Whatever, consisting of album reviews from the year 2016. He currently hosts panel show Hypothetical alongside Josh Widdicombe, food podcast Off Menu with fellow comedian Ed Gamble and music podcast James Acaster’s Perfect Sounds from the BBC.