Irvin D. Yalom is an American psychiatrist and psychotherapist known for his contributions to the field of psychotherapy. He is particularly recognized for his work in existential psychotherapy, which focuses on the human experience and the search for meaning. Yalom has authored several influential books, both fiction and non-fiction, that explore psychological themes and therapeutic practices. Yalom's notable works include The Gift of Therapy and When Nietzsche Wept, which blend personal insights with philosophical concepts. His approach emphasizes the therapeutic relationship and the importance of addressing existential concerns such as death, freedom, and isolation in therapy.