Martin Seiler, who was born in 1964, held a variety of HR positions at Deutsche Telekom before joining DB. He most recently served as Director of Human Resources and Industrial Relations, a position he assumed in June 2015. In that role, he was responsible for 70,000 employees at Telekom Deutschland and, as Management Spokesperson for Telekom Training, was also responsible for all the vocational trainees and cooperative education students at the company.

Seiler began his career in 1980 at Deutsche Post in Baden-Baden. After working for the German Postal Workers Union (which would later merge with ver.di, the German United Services Trade Union), and in that capacity serving as a member of the European Commission's Social Dialogue, Seiler took on a management role at Deutsche Post in Bonn in 2003. He held a variety of management positions during his tenure.

In 2004, Seiler became HR Director for the Express and Logistics business segment, where his responsibilities included integrating the HR work of the DHL companies in Germany. As HR Director for Express Deutschland, Seiler represented the company during many negotiations between employer and employee representatives. Beginning in 2009, he was also responsible for human resource management at all the DHL companies in Switzerland and Germany.

Seiler joined Deutsche Telekom in 2010 as Director of Human Resources and Industrial Relations for Deutsche Telekom Kundenservice GmbH.