Hassar may be:

• A common name for Callichthys callichthys
• A common name for Hoplosternum littorale
• Hassar (fish), a genus of doradid catfishes
• Abu Bakr al-Hassar, 12th century Muslim mathematician who first used the fraction bar, and writer
• Joudia Hassar-Benslimane (1943–2018), Moroccan historian and archeologist

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