Étienne-Constantin de Gerlache (1785-1871) was a Belgian politician. He was born in Luxembourg, and died in Paris. Gerlache studied law. When Napoleon was emperor, Gerlache was part of the Supreme Court in Paris. When Belgium and the Netherlands joined, he was part of a court in Liège. During this time, he wrote several articles about law subjects. In 1826, he became a member of the States General of the Netherlands. During that time he became known for his eloquence as the leader of the Catholic opposition. In 1831, he became the first prime minister of Belgium. Because he was a catholic, and all the other members of the government were liberals, this led to many conflicts. In the end, he resigned his post as prime minister. In 1832, he was elected head of the Supreme Court of Belgium. In church matters, he was an ultramontanist.