Soren Kierkegaard - Mystic, Existentialist
Kierkegaard was a mystic and an existentialist. (Existentialism: an atheistic philosophy in which everything is relative; there are no absolute truths)
(from Faith Undone, chapter 2):
In a dissertation at Purdue University, called "Faith and nothingness in Kierkegaard: A mystical reading of the God-relationship," the writer said of Kierkegaard:
[He] has marked structural similarities to mystics such as Eckhart, who is warmly received by the Japanese philosophical tradition, particularly in the writings of its Zen and Pure Land Buddhist representatives.