Stefan Seidler is a Danish-German politician of the South Schleswig Voters' Association (SSW), the party representing the interests of the Danish and Frisian minority populations in Germany.

In Aarhus, he was deputy chairman of Radikal Ungdom, the youth wing of the Danish Social Liberal Party, and later was that party's candidate for both the Danish Parliament and the European Parliament.

[5] He was a member of Flensburg's city council, worked as a political consultant in Southern Denmark, and in 2014, became Schleswig-Holstein's coordinator of relations with the Danish government.

[3] In 2021, he contested the constituency of Flensburg – Schleswig, located at the German-Danish border, for the SSW.

He was defeated by Robert Habeck from Alliance 90/The Greens, but won a seat on the party's state list.