Søren Kierkegaard was a Danish philosopher, theologian, and religious writer who lived from 1813-1855. He is known for criticizing idealist philosophers and giving priority to real human life rather than abstract thoughts. He was also critical of the state of Christianity during his lifetime, particularly the Church of Denmark.
His early works were written under a number of pseudonyms which interacted and argued with each other, each exploring a different viewpoint in depth. His writings gained fame through the mid 20th-21st centuries, influencing a number of modern philosophers with concepts such as angst and the importance of the individual.