Abigail Thorn (born 24 April 1993) is an English YouTuber, actress, and playwright.

Thorn created the YouTube channel Philosophy Tube in 2013, when she sought to provide free lessons in philosophy in the wake of the 2012 increase in university tuition fees in England. In 2018, her videos became more theatrical, beginning to incorporate dramatic studio sets, lighting, costuming and makeup. The channel has been positively received by critics and has over one million subscribers.

In 2019, Thorn hosted a livestream 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 charity. In September and October 2022, The Prince—a play written by and starring Thorn—ran Off West End. The transgender-themed work is based on characters in Shakespeare's Henry IV, Part 1 becoming self-aware.

Thorn publicly came out as a transgender woman in January 2021, with the video Coming Out As Trans – A Little Public Statement and the more theatrical Identity: A Trans Coming Out Story.