Poland

The Jagiellonians ruled Poland until 1573, when Sigismund II Augustus died childlessly.

An excerpt from the article 31 facts about Poland
After the king's death, a free election was introduced in the republic, which means that the nobility elected the king. Most of the elected rulers were not interested in the development of the country or were not competent in this matter. In the last century of the free election period, Poland's importance in the international arena gradually declined, which led to the partitions.