Juho Sylvester Perälä (24 August 1887 in Teuva – 20 January 1938 in Medvezhyegorsk; also known as Sylvester Perälä; named as Soviet citizen Иван Иванович Перяля) was a Finnish farmer and politician.
In 1925 Perälä joined the still illegal Communist Party of Finland (SKP).
He was a member of the Parliament of Finland from 1928 to 1930, representing the pro-communist but till then legal Socialist Electoral Organisation of Workers and Smallholders (STPV), which was banned in 1930.
In July 1930, Perälä was abducted by activists of the anti-communist Lapua Movement, which forced him to cross the border to the Soviet Union.
As one of the victims of the Great Purge, he was arrested by the NKVD on 10 December 1937, sentenced to death and shot in Medvezhyegorsk on 20 January 1938.