What was Thomas Clarkson known for?

Thomas Clarkson (28 March 1760 – 26 September 1846) was an English abolitionist and a leading campaigner against the slave trade in the British Empire. He helped found The Society for Effecting the Abolition of the Slave Trade (also known as the Society for the Abolition of the Slave Trade) and helped achieve passage of the Slave Trade Act of 1807, which ended British trade in slaves.

In his later years, Clarkson campaigned for the abolition of slavery worldwide; it was then concentrated in the Americas. In 1840, he was the key speaker at the Anti-Slavery Society's (today known as Anti-Slavery International) first conference in London, England which campaigned to end slavery in other countries.