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Poet, Fernando Pessoa is best known for his innovative use of heteronyms, distinct literary personas with their own unique styles and biographies. Through these heteronyms, Pessoa explored a wide range of themes, including existentialism, symbolism, and the nature of identity. His most famous heteronyms include Alberto Caeiro, Ricardo Reis, and Álvaro de Campos, each representing different aspects of Pessoa's complex and multifaceted personality.