Pekka Valter Mattias Streng (April 26, 1948, Sysmä – April 11, 1975) was a Finnish musician who had a notable influence on progressive rock in Finland.

Streng died of cancer at the age of 26. He knew about his disease throughout his career and the awareness of his forthcoming death can be heard from both his lyrics and music. During his short career he made two albums, which were published by Love Records. He wrote the songs and lyrics (in Finnish), and performed vocals and acoustic guitars on the albums. On the first one, Magneettimiehen kuolema (1970), he collaborated with Tasavallan Presidentti, a renowned Finnish prog band of the time. On Kesämaa (1972), various other noted musicians such as Olli Ahvenlahti and Hasse Walli took part in the studio sessions.