Lagercrantz was born in Stockholm, Sweden, the son of bank director Carl Lagercrantz and Countess Agnes Hamilton. He married Martina Ruin, daughter of Professor Hans Ruin and Karin Sievers, in 1939. Lagercrantz is the father of actress Marika Lagercrantz and author David Lagercrantz. His sister Lis Asklund was an author, social worker, curator, and program producer for Sveriges Radio. His nephews Lars Lönnroth and Johan Lönnroth are also famous in their own right. Lagercrantz commanded considerable influence as a critic and publicist. He became an expert of sorts in literary biography, and several of his studies on important Swedish writers are still cornerstones of Swedish literary studies, in particular, his biography of August Strindberg and his portrait of his friend Gunnar Ekelöf, Jag bor i en annan värld men du bor ju i samma. During the latter part of his professional life, Lagercrantz' concerns in his role as literary critic and cultural pundit progressed from the strictly aesthetic to the political. In 1958, he published a biography of the late poet Stig Dagerman which was severely criticized by a young Beppe Wolgers for being confined to Dagerman's "dark predicament" and not completely representing a man "who paid such great interest to cinema as well as football". Lagercrantz' political engagement became apparent during his time at Dagens Nyheter, where he was head of the cultural section from 1951 and editor-in-chief from 1960 on. He was an influential, albeit controversial, voice in the political and cultural radicalism of the 1960s and 1970s, assuming a crucial role in the national secularization debate. Lagercrantz in his public role gave rise to strong emotions. His cultural radicalism in particular was perceived as provocative in light of his aristocratic background. Lagercrantz was widely criticized for the conciliatory and fairly positive appraisals of Communism that he published in Dagens Nyheter after travelling as a journalist to the Soviet Union and China. Lagercrantz dwelt on parts of this in his autobiographical works. His upper-class childhood and adolescence are the subject of Min första krets, and the turbulence of his time at Dagens Nyheter is the topic of his memoir Ett år på sextiotalet. Olof Lagercrantz grew up in Falköping and in 2001 was awarded the title of Honorary Resident of Skaraborg by the Skaraborg Academy in tribute to the fact he had wielded one of the mightiest pens of the 20th century.
