Yosa Buson
The most extensive use of haiku in science fiction is in David Brin's Uplift Universe (especially in the novel Startide Rising), where the uplifted dolphins speak a haiku-like language called Trinary. He has characters quoting haiku by Kobayashi Issa and Yosa Buson, and has them spontaneously writing their own haiku. Outside of his Uplift Universe, Brin has haiku as chapter epigrams in his novel "The Postman".