Opper may refer to:

• Bernard Opper (1915–2000), American basketball player
• Clarence V. Opper (1897–1964), United States Tax Court judge
• Don Keith Opper (born 1949), American actor, writer, and producer
• Frederick Burr Opper (1857–1937), American cartoonist
• Niko Opper (born 1992), German footballer

• Baltimore Zoo
• Baltimore–Washington Superconducting Maglev Project
• Baltinglass
• Balti (people)
• Balti Power Plant
• Baltische Landeswehr
• Baltischport
• Balti script
• Baltissare Castiglione
• Baltistan Peak
• Baltistan Wildlife Sanctuary
• Baltis Vallis
• Baltit
• Baltit Fort
• Baltit fort
• Balti Triangle
• Balti wine
• Balti Wines
• Baltix
• Baltiyska
• Baltiyskaia
• Baltiysk (air base)
• Baltiyskaya (Saint Petersburg Metro)
• Baltiyski
• Baltiyskii