Cognomen Willoughby (Willoughby 
) , around the globe, is a common last name. The family name Willoughby is habitual in Belize, where it is quite a common surname, Barbados, and New Zealand, where it is quite a rare surname. Measured by absolute frequency, it is the most numerous in the United States, the United Kingdom, and Australia. Much less frequently, Willoughby is the forename as well as the last name.
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| Willoughby | United Kingdom, United States, Australia, South Africa, Canada |
| robert de willoughby, 1st baron willoughby de eresby English nobleman, GB (b. 1260) |
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| richard de willoughby Lord Chief Justice of England and Wales (b. 1290) |
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| john willoughby English soldier (c.1328–1372) (b. 1328) |
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| robert willoughby English soldier (b. 1349) |
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| william willoughby, 5th baron willoughby de eresby English peer, GB (b. 1370) |
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| hugh willoughby English landowner (b. 1380) |
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| robert willoughby English baron and soldier of the Hundred Years' War (b. 1380) |
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| sir thomas willoughby (1387-1432) (b. 1387) |
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| margaret willoughby English heiress (c.1401–1493) (b. 1401) |
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robert willoughby English commander against Cornish rebels for Henry VII, GB (b. 1452) |
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| joan willoughby, 7th baroness willoughby de eresby English baroness (b. 1425) |
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| robert willoughby Peerage person ID=366400 (b. 1427) |
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| john willoughby (b. 1421) |
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| sir william willoughby Peerage person ID=2672, GB (b. 1432) |
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| henry willoughby English gentry (c.1451–1528), GB (b. 1451) |
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