The M9 Pistol was the former service pistol of the U.S. Army until it was recently replaced by the M17.  The M9 was also featured prominently in action movies from the 80's and 90's making it one of the easiest to recognize pistols to date. 

Papago Arms US M9 Type Full Stainless Steel Black Conversion Kit for Marui M9A1 GBB
High-quality stainless steel Construction
This Kit can Make Your Pistol More Realism
Suitable For Tokyo Marui M9A1 Series Airsoft Gas Blow Back GBB Pistol