4th Legion may refer to:

• Legio IV Macedonica founded in 48 BC
• Legio IV Scythica founded c. 42 BC by the general Mark Antony
• Legio IV Flavia Felix founded in AD 70 by the emperor Vespasian from the ashes of the Legio IV Macedonica
• Legio IV Martia
• Legio IV Italica founded in AD 231 by emperor Alexander Severus

• Thesaurus Linguae Sericae
• The Sausage Factory
• The Sausalito Library
• The Savage Altar
• The Savage and the Hungry
• The Savage Curtain (TOS episode)
• The Savage Detectives
• The Savage Dragon
• The Savage Dragon: Sex & Violence
• The Savage Empire
• The Savage Frontier
• The Savage Land (opera)
• The Savage Lands
• The Savage Nation (radio)
• The Savage Poetry
• The Savage Rose
• The Savages (film)
• The Savage She-Hulk
• The Savages (TV series)
• The Savage Time
• The Savage Time (Justice League)
• The Savage Time (Justice League episode)
• The Savannah Arts Academy
• The Savannah Country Day School
• The Save-Ums!