G13 may refer to:

• G-13 (cannabis), a type of cannabis
• County Route G13 (California)
• G13 Baobab Alliance, a political alliance in Benin
• G13 carbine, a proposed Georgian firearm
• Gate 13, a group of supporters of the Greek football club Panathinaikos
• HMS G13, a Royal Navy G-class submarine
• Logitech G13, a computer keyboard
• Suzuki G13, an automobile engine
• G-13, a Swiss postwar version of the Jagdpanzer 38 Hetzer tank destroyer
• G13, a type of bi-pin lamp base