J21

J21 or J-21 may refer to:

Vehicles

Aircraft

• Junkers J 21, a German reconnaissance aircraft
• SAAB J 21, a Swedish fighter
• Shenyang J-21, a Chinese prototype fighter
• Soko J-21 Jastreb, a Yugoslav light attack aircraft

Locomotives

• LNER Class J21, a British steam locomotive class

Ships

• , a Bangor-class minesweeper of the Royal Navy and Royal Canadian Navy
• , an Östergötland-class destroyer of the Swedish Navy
• , a survey ship of the Indian Navy

Other uses

• Bronchiolitis
• County Route J21 (California)
• Elongated pentagonal rotunda, a Johnson solid (J₂₁)