Otus may refer to:

• Otus (education), a K-12 educational technology company
• HMS Otus, two ships in the Royal Navy
• Otus (bird), genus of owls
• Otus (mythology), giant in Greek mythology, brother of Ephialtes, one of Aloadae
• Otus of Cyllene, hero in Greek mythology, killed by Hector in Trojan War
• USS Otus (ARG-20) (1940–1946), an internal combustion engine repair ship
• "Otus the Head Cat", weekly column in the Arkansas Democrat-Gazette by Michael Storey
• Otus (lens), high-performance lens series by Carl Zeiss AG
• Tonmi Lillman or Otus (1973–2012), member of a band Lordi
• "of the United States", as in POTUS (President of the United States), FLOTUS (First Lady of the United States), and SCOTUS (Supreme Court of the United States)
• Moto E (2nd generation) 3G, a Motorola Android smartphone, codename otus
• Otus, a playable character from the 2016 Video Game Owlboy from D-Pad Studio
• Operational taxonomic unit, operational taxonomic units in biology

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