A German surname-style name related to Thiel, itself tied to old forms of Matthias.
Thielen is a German and Dutch family surname that has migrated, as surnames often do in American naming, into use as a given name. The surname traces back to the Low German and Dutch dialect regions, where it developed as a diminutive or patronymic form of Thiel — itself derived from the Old High German personal name Theudilo or Theodilo, built on the element theud, meaning people or folk, the same Germanic root found in Theodoric, Theobald, and ultimately in modern Theodore.
Thielen thus carries within it a lineage reaching back to the tribal identities of the early Germanic peoples. In contemporary American culture, the name gained particular visibility through Adam Thielen, the Minnesota Vikings wide receiver born in 1990 in Marshall, Minnesota, who became one of the NFL's most productive pass-catchers in the late 2010s. His story — an undrafted player who became a Pro Bowl selection through relentless work — gave the name an association with perseverance and achievement that resonates for parents in the upper Midwest, where German and Scandinavian surnames have long been repurposed as first names.
The use of surnames as given names has ancient roots — in English naming history, it became fashionable in the 17th century as a way of honoring maternal family lines — and it experienced a major revival in late 20th-century America. Thielen fits comfortably in the tradition of two-syllable Germanic surname-names like Brennan, Griffin, or Holden: strong, distinctive, and carrying the weight of a history longer than the individual who bears it.