Johns Hopkins University

This is the correct name of the University in the USA, in Baltimore, Maryland. The instinct of most native speakers of English is to assume that the name 'John' is a forename, and should therefore be in the singular form. It isn't; and the seemingly natural John Hopkins University is an error.

Don't make it!

Etymological note: "The first name of the [founder of the University,] Johns Hopkins comes from the surname of his great-grandmother, Margaret Johns, who married Gerard Hopkins" (Wikipedia, 2020). That was in 1700. One of their children was named Johns Hopkins, uniting their two surnames; a grandson, and namesake, of his, born in 1795, became the phenomenally wealthy philanthropist and founder of the Johns Hopkins University (and The Johns Hopkins Hospital) in Baltimore.