Pionýr (literally: Pioneer), officially Pioneer Organization of the Socialist Youth Union (Czech: Pionýrská organizace Socialistického svazu mládeže, PO SSM; Slovak: Pionierska organizácia Socialistického zväzu mládeže, PO SZM), was a youth Marxist-Leninist organization in communist Czechoslovakia that was a subdivision of the Socialist Youth Union.

Original pioneer activities included old paper or herb collecting, described as "voluntary help for Czechoslovak industry".

Collecting was a nationwide competition, and the winning pioneer team received a prize and media attention, and a positive reference for their later career.

The most popular activity were the summer camps, which sometimes involved the hosting of youth communist organizations from the whole Eastern Bloc.

The organisation's most controversial activity was young pioneers being encouraged to denounce their parents, like the Soviet hero Pavlik Morozov.