Baron Bo Gustaf Bertelsson Carpelan (25 October 1926 – 11 February 2011) was a Finland-Swedish poet and author.

Carpelan, who wrote in Swedish, composed numerous books of verse, as well as several novels and short stories.

His poem, Winter was Hard, was set to music by composer Aulis Sallinen.

He also wrote the libretto for Erik Bergman's only opera, Det sjungande trädet.

Carpelan went to Svenska normallyceum i Helsingfors and then studied history of literature at University of Helsinki.