The Prussian Kings were the rulers of the Kingdom of Prussia, which played a significant role in European history from the 18th to the early 20th century. The most notable among them was Frederick II, also known as Frederick the Great, who reigned from 1740 to 1786 and is remembered for his military successes and cultural contributions. Under his leadership, Prussia became a major European power. The Kingdom of Prussia eventually became part of the German Empire in 1871, following the unification of Germany. The last king, Wilhelm II, ruled from 1888 until the abdication of the monarchy in 1918, marking the end of the Prussian royal lineage and the establishment of the Weimar Republic.