Stephan Franz Lajos (or Ludwig) Haynald (October 3, 1816, at Szécsény – July 3, 1891, at Kalocsa) was a Hungarian Archbishop of Kalocsa-Bács, naturalist, and cardinal.

The prince-primate, József Kopácsy, appointed him his secretary in 1846,[1] but before he had entered upon the duties of that office, dispatched him abroad to study the training of pastors and ecclesiastical administration.

At the close of the Revolutionary War he was restored to his office; on 15 September 1851, he was appointed coadjutor to the Bishop of Transylvania, Nicholas Kovács, whom he succeeded on 15 October 1852.

[2] Pope Leo gave him his red galero and assigned him the titular church of Santa Maria degli Angeli e dei Martiri on 22 September.

While still a young priest he devoted himself to botany and made a large collection of plants and of books, which subsequently came into the possession of the Hungarian National Museum.