Abigail Thorn (born 24 April 1993) is a British actress and YouTuber who produces the YouTube channel Philosophy Tube. The channel began in 2013, when Thorn sought to provide free lessons in philosophy in the wake of the 2012 increase in British tuition fees. Her videos discuss philosophy through a left-wing perspective often informed by developments in contemporary politics.

Since 2018, the channel has become more theatrical and often makes use of dramatic studio sets, lighting, costuming, and makeup. Philosophy Tube has been positively received by critics, and as of January 2021, the channel has around 830,000 subscribers. In 2019, Thorn hosted a live-stream on Twitch in which she read plays from the Complete Works of Shakespeare for the mental health charity Samaritans. The stream lasted five days, featured a number of guests, and raised over £100,000 for the Samaritans.

Thorn publicly came out as a transgender woman in January 2021.