M45

M45 or M-45 may refer to:

In science:

• Messier 45, an open star cluster also known as the Pleiades
• 45th known Mersenne prime
• M45 genetic marker, a genetic marker on the Y-chromosome
• Yahoo M45, a supercomputing cluster

In transportation:

• Infiniti M45, a luxury car
• M45 motorway, a motorway in England
• M-45 (Michigan highway), a state highway in Michigan
• M-45, a motorway in Spain

In firearms and military equipment:

• Carl Gustav M/45, a Swedish submachine gun
• M45 SLBM, a French submarine-launched ballistic missile
• M45 Quadmount, a weapon platform with four M2 Browning machine guns
• MEU(SOC) pistol, the standard-issue side arm for the Force Recon Element of the United States Marine Corps' Marine Expeditionary Units.
• A variant of the M26 Pershing medium tank, initially named T26E2.