Rontgen was born in Lennep in Rhenish Prussia as the only child of a merchant and manufacturer of cloth. His mother was Charlotte Constanze Frowein of Amsterdam. In March 1848, the family moved to Apeldoorn and Wilhelm was raised in the Netherlands.
Rontgen was married to Anna Bertha Ludwig and had one child, Josephine Bertha Ludwig. Adopted at age 6, in 1887, she was the daughter of Anna's brother. He died on 10 February 1923 from carcinoma of the intestine. It is not believed his carcinoma was a result of his work with ionizing radiation because of the brief time he spent on those investigations, and because he was one of the few pioneers in the field who used protective lead shields routinely.
In keeping with his will, all his personal and scientific correspondence were destroyed upon his death.