Class S
# Class S

Class S may refer to:

* Class S (culture), early 20th century Japanese social practice of female romantic friendships, and a literary genre depicting this practice
* Class S, a stellar classification for carbon stars
* Baltimore and Ohio class S, American steam locomotives
* BNCR Class S, Irish steam locomotive
* GNRI Class S, Irish steam locomotive
* South African Class S 0-8-0, steam locomotives
