YF, Y.F., or Yf can refer to:

Fictional vehicles:

• YF-19 Alpha One Excalibur, a spacecraft in the anime series Macross
• YF-21 Omega One, a spacecraft in the anime series Macross

Real vehicles:

• A US Navy hull classification symbol: Covered barge, self propelled (YF)
• A US Air Force aircraft designation: YF - Prototype Fighter
• A series of Chinese rocket engines, including:
  • YF-50t
  • YF-73
  • YF-75
  • YF-77
  • YF-100
• Yamaha YF 60, an all-terrain vehicle

Squadrons:

• YF, the MODEX code for Marine Heavy Helicopter Squadron-462 (The Heavy Haulers, or its nickname "The Screw Crew")