21st Army may refer to:

• 21st Army (Wehrmacht)
• 21st Army (Soviet Union)
• Twenty-First Army (Japan)
• 21st Army Group, Britain
• 21st Group Army, China

• Cantus Verkehrsgesellschaft
• Cantus (vocal ensemble)
• Cantuta
• Cantuta (disambiguation)
• Cantuzumab
• Cantuzumab mertansine
• CANTV
• Cantv
• CANTV Movilnet
• Cantv.net
• CANTV Servicios
• Can't Wait
• Can't Wait Another Day
• Can't wait another minute
• Can't Wait Another Minute
• Can't Wait Too Long
• Can't Wait to See the Movie
• Can't Wait Until Tonight
• Cantwara
• Can't we all just get along
• Can't we all just get along?
• Can't We Fall In Love Again?
• Can't We Fall in Love Again?
• Can't We Just Sit Down (And Talk It Over)
• Cantwell