What ended slavery officially?

Slavery was ended in different countries at different times.

Many Latin American countries ended slavery during their wars for independence (1810-1826) in order to curry favor with enslaved populations and secure their help in fighting off Spanish power. The first major power to ban slavery was the United Kingdom, which did so in the Slavery Abolition Act of 1833*. Several other European countries followed suit. The United States ended Slavery through the Thirteenth Amendment to the US Constitution in 1863. Brazil ended slavery in 1888. Many countries, especially in the Third World, retained slavery well into the 20th century. Saudi Arabia, as one example, only outlawed slavery in 1962. The last state where slavery was legal was Mauritania, which officially banned the practice in 2008, but it is still estimated that 19% of the Mauritanian population is made up of slaves.

*France under the First Republic did ban slavery in 1794, but slavery was reinstated by Consul Napoleon in 1802.