Jekyll and Hyde

American  

[jek-uhl, jee-kuhl] / ˈdʒɛk əl, ˈdʒi kəl /

noun

1. a person marked by dual personality, one aspect of which is good and the other bad.

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Jekyll and Hyde British  

/ ˈdʒɛkəl, haɪd /

noun

1. 1. a person with two distinct personalities, one good, the other evil

   2. ( as modifier )

      a Jekyll-and-Hyde personality

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Jekyll and Hyde Idioms  

1. A personality alternating between good and evil behavior, as in You never know whether Bob will be a Jekyll or a Hyde. This expression comes from Robert Louis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde (1886). Also see lead a double life.

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Etymology

Origin of Jekyll and Hyde

After the protagonist of Robert Louis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde (1886)

Example Sentences

Jekyll and Hyde is Steady Eddie by comparison.

From BBC • Feb. 13, 2026

Brighton are a real Jekyll and Hyde side at the moment, but I always feel they will do well at home - they have only lost once there this season.

From BBC • Dec. 18, 2025

It’s a durable trope that’s worked from Jekyll and Hyde to Kirk and Khan, but Heller is less invested in identifying winners and losers.

From Los Angeles Times • Jul. 26, 2023

The underlying stocks in the portfolio — including Tesla, Amazon and Nvidia — had Jekyll and Hyde performances, too, depending on which month you looked at them.

From New York Times • Apr. 7, 2023

Gradually, however, like Jekyll and Hyde, one personality began to predominate.

From "Kaffir Boy: An Autobiography" by Mark Mathabane