Fosi is a Germanic tribe.
Fosi or FOSI may also refer to:
People Polataivao Fosi Schmidt (1933–2005), boxer and Minister of Labor for Samoa Fosi Pala'amo (born 1976), New Zealand professional rugby player of Samoan descent
Other uses Formatting Output Specification Instance, a stylesheet language for SGML and XML Family Online Safety Institute, an international nonprofit organization Friends of Stradbroke Island an environmental lobby group on North Stradbroke Island in Queensland, Australia