Cognomen Gacy (جاسى 
, Gacy 
, 盖西 
) , in all the world, is a rare last name. The surname Gacy is characteristic of Egypt, where it is a rare surname, the United Kingdom, where it is a very rare surname, and the United States, where it is an extremely rare surname. Not in comparison with a country's population, this name is the most popular in Egypt, China, and the United States. More frequently, Gacy is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| جاسى | Egypt |
| Gacy | Philippines, United States, United Kingdom, Brazil, Democratic Republic of the Congo |
| 盖西 | China |
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john wayne gacy American serial killer and torturer (1942-1994), US (b. 1942) |
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madonna wayne gacy Musical artist, US (b. 1964) |
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| jean gacy 16th-century Franciscan writer, FR |
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| joe gacy American professional wrestler, US (b. 1987) |
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