Hamnett, and its spelling variants Hamnet and Hannett, is a personal name (now usually or only found as a surname).
The earliest attested forms of this name occur in Old German, as Haimo.
The form Haimon was then combined with the Anglo-Norman diminutive suffix -et, giving the pet-name Hamunet.
In 1881, 991 people in Great Britain had the name, being clustered in the south-west of England, especially Devon.
Meanwhile, Irish bearers of the name around the middle of the nineteenth century clustered in Dublin.