Theon may refer to:
- Theon of Samos, painter
- Theon of Smyrna (c. 70–c. 135), philosopher and mathematician
- Theon of Alexandria (c. 335–c. 405), last curator of the Alexandrian Library
- Theon (1st century BC), literary critic and lexicographer
- Theon (rhetorician) (c. 500), teacher of Damascius
- Theon, vocalist for Lovex
- Theon Greyjoy, a character in George R R Martin' fantasy series A Song of Ice and Fire
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