P. J. (Pekka Juhani) Hannikainen (December 9, 1854 Nurmes – September 13, 1924 Helsinki) was a Finnish composer and music lecturer at the Jyväskylä Seminary. He also worked as a choir director and founded the Ylioppilaskunnan laulajat and the Jyväskylä amateur orchestra.
During his lifetime, Hannikainen composed close to three hundred songs inspired by choral activities. Most of the songs are choral songs for mixed choirs, but he also composed for other choral forms. The songs dating to the rising period of the national awakening are related to the Finnish tradition. Hannikainen was self-taught as a composer, except for a few theory lessons.