AT-4 may refer to:

• AT4, a Swedish unguided, portable, single-shot anti-tank weapon
• AT-4 Spigot, a Soviet guided anti-tank missile
• Curtiss AT-4 Hawk, U.S. Army biplane advanced trainer of 1927

• G. M. Kert
• GMK Ltd.
• GML-1
• GM L33 engine
• GM L3B engine
• GM L59 engine
• GM L76 engine
• GM L77 engine
• GM L98 engine
• GMLAN
• GML Application Schemas
• GM LD engine
• GM LM4 engine
• GM LM7 engine
• GM LQ4 engine
• GM LQ9 engine
• GM LR4 engine
• GM LS3 engine
• GM LS7 engine
• GM LS9 engine
• GM LS-series engine
• GMM-120 self-propelled mortar
• GMM 25
• G.M. (magazine)
• GM Manufacturing Poland