The Night of Agony (Portuguese: Noite da agonia) was a historical event in the Brazilian Empire, occurring in the pre-dawn hours of 12 November 1823, when emperor Dom Pedro I ordered the army to invade and dissolve the Brazilian constitutional assembly. The assembly resisted for several hours, but in the end was dissolved and a few of its members were imprisoned and deported, including the brothers José Bonifácio de Andrada e Silva and Martim Francisco Ribeiro de Andrada, as well as Antônio Carlos Ribeiro de Andrada Machado e Silva.
The following year, on March 25, 1824, a new Imperial Constitution was adopted, which designed an Executive, Legislative, and Judicial branch, but also invested in the Emperor the title of "Moderator", acting as a neutral intermediary between the branches.