73 may refer to:

• 73 (number)
• one of the years 73 BC, AD 73, 1973, 2073
• 73 (magazine), a United States-based amateur radio magazine
• 73 Best regards, a popular Morse code abbreviation
• No. 73, a British 1980s children's TV show
• Nickname for the Boeing 737 airplane

• Cryptocycloceras
• Cryptocynodon
• Cryptodacus
• Cryptodaphne
• Cryptodaphne affinis
• Cryptodaphne gradata
• Cryptodaphne kilburni
• Cryptodaphne rugosa
• Crypto (Destroy All Humans!)
• Cryptodiaporthe
• Cryptodictyon
• Cryptodifflugia
• Cryptodiramorpha
• Cryptodire
• Crypto (disambiguation)
• Cryptodiscus
• Cryptoditha
• Cryptoditha elegans
• Cryptodontia
• Cryptodontidae
• Cryptoendolithic
• Crypt of Cthulhu
• Cryptofiction
• Crypt of Lieberkuehn
• Crypt of Lieberkühn