Threatt
An English surname most likely from a nickname for a bold or menacing person, or a spelling variant of Threat.
The #9,199 most common surname in the United States (2010 Census) — about 1 in every 87,093 Americans shares it.
Etymology
Threatt is best understood as an English surname from the word "threat," used as a nickname for someone seen as intimidating, forceful, or troublesome. The doubled final consonant is a spelling variant, not a separate root, and may reflect older local or clerical spelling habits. In some cases it may also represent a variant of Threat, itself from the same word.
History
As with many short English surnames, Threatt likely began as a descriptive byname and later stabilized as a family name. The form with doubled -t is especially found in English-derived surname traditions and may have persisted through migration and American record-keeping. The modern US spelling appears to be relatively uncommon but established.
Origin
Regions
Variant spellings
Fun fact
Because surnames often froze one of several historical spellings, families with the same root can appear in records as Threat, Threatt, or Thrett.