Seiichi Niikuni (????, Niikuni Seiichi, December 7, 1925 – August 23, 1977) was a Japanese poet and painter.
He was one of the foremost pioneers of the international avant-garde concrete poetry movement, creating works of calligraphic, visual and aural poetry.
He is recognized as one of the most important poets of recent times in Japanese and German textbooks.It is said that during his later years, he started to prefer the old kanji orthography form of his name, ????.