When people search this question, they usually mean the 18th-century English performer Thomas Wadhouse (often spelled Thomas Wedders). But the correct answer depends on category.
Historical (ever recorded)
Victorian summaries repeat a length of about 7.5 inches (19 cm) for Wadhouse/Wedders. The sources are brief and non-clinical, but consistent enough that record keepers list him as the historical case.
Modern (living, verified)
For living people, Guinness applies strict protocol. For years, Mehmet Özyürek held a verified measurement of 8.8 cm (3.46 in). Any new claimant must exceed that under the same rules to be recognized today.
Why both answers matter
The historical figure explains why the story captures imaginations; the modern figure explains what counts as proof now. Confusing the two leads to viral headlines but muddled facts.
How museums and media illustrate the story
Most outlets show a wax head and credit Guinness for context. The wax is a modern reproduction, not a cast from Wadhouse’s body. Treat it as a visual aid, not evidence.