C7 or C-7 may refer to:

• The Diemaco C7, a rifle.
• The C-7 Caribou, a miltary transport aircraft.
• C7 Sport, a pay-TV service in Australia.
• HMS C7 , a C-class submarine of the Royal Navy.
• USS Cincinnati (C-7) , a protected cruiser of the United States Navy.
• C7, an international standard paper size (81×114 mm), defined in ISO 216.