Stefan Marschner received a Jesuit education from age 11 to age 17, joined the Society of Jesus at St. Andrä in September 1869, and was ordained in July 1882. He taught at Mariaschein for two years and obtained a tertianship at Staravies, France.

Visiting Fr. Anton Strele inspired him to join the Australian mission¹, and he arrived with Strele in Darwin in February 1889. He went to Old Uniya on 3 October 1889 and he and Fr. Donald McKillop established the short-lived Sacred Heart Station at Serpentine Lagoon (see Daly River Missions). In 1891 he was the only priest at Serpentine Lagoon assisted by two Brothers and learned the local language. Fr. Marschner knew how to cure tobacco, and experimented with various crops.

He joined the amalgamated mission at new Uniya in 1891 but in June 1892 he was ordered to return to Sevenhill to recuperate from serious illness, together with Fr. Strele. Fr. Marschner worked at Burra (Kooringa) and Sevenhill until he was called back to the north in March 1895. Around this time he gave a hopeful press interview about the state of the mission. However the mission was struggling with internal tensions. During the next few years two official visitations resulted in the re-arrangement of the staff so that Marschner was left as the only priest at the mission with five Brothers. He was no longer enthusiastic about the mission.² He was at Uniya during the great flood in 1899 and wrote the final entries in its diary from 15 May to 14 June 1899.

In November 1899 Fr. Marschner returned to Austria via China. He became a minister at Trynau (Hungary), later worked at Innsbruck (Austria), Laibach (Bosnia) (1903-1908) and Mariaschein (now Bohosudov in the Czech Republic) where he died from a lung infection. He was known for his 'humanity and kindness, humility, and quiet conversation'.³