J11 may refer to:

• Fiat J 11, an Italian sesquiplane fighter in service with the Swedish Air Force
• Junkers J 11, a German ground-attack aircraft
• Shenyang J-11, a Chinese jet fighter

• James Comet J11, an English motorcycle
• Nissan Qashqai J11, a Japanese SUV

• GSR Class J11, an Irish steam locomotive
• LNER Class J11, a class of British steam locomotives

• HMS Bramble (J11), a Halcyon-class minesweeper of the Royal Navy
• HSwMS Visby (J11), a Visby-class destroyer of the Swedish Navy

• County Route J11 (California)
• DEC J-11, a microprocessor chip set
• Gyroelongated pentagonal pyramid, a Johnson solid (J₁₁)

• JII (disambiguation)