Tadeusz "Thaddeus" F. Zielinski (1916 – 11 Aug 1990) was a bishop of the Polish National Catholic Church (PNCC).

He was consecrated in Buffalo, New York on September 2, 1954[1] and served as Prime Bishop of the Polish National Catholic Church from 1969[2] until his retirement in 1978.

Zielinski died on August 11, 1990, at the age of 85 in Scranton, Pennsylvania.

[4] During his tenure, the use of the English language, in place of Polish, was popularized with the translation of liturgies and hymns.

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