Old boy

Old boy may refer to:

In Britain, any male former pupil of a school
A cadet who has attended St. John's Military School.
Old Boy (manga), a manga series
Oldboy a 2003 South Korean film based on the Japanese Manga "Old Boy"
Old boy network, social and business connections among former pupils of top male-only schools
Reginald "Old Boy" Wilmot (20th century), Australian journalist