David Wagner

Wagner was born in Frankfurt, West Germany. His biological father is from Thailand, his mother is German. Before his birth, Wagner's mother married an American. Wagner was a journeyman striker for his playing career, playing primarily for Mainz 05, Darmstadt 98, FC Gütersloh, and Schalke 04. He also had short stints at Waldhof Mannheim, Eintracht Frankfurt and TSG Weinheim and Germania Pfungstadt. He enjoyed his best spell at Mainz scoring 19 times in his four years at the club. Former teammate and lifelong friend Jürgen Klopp recalled that "he wasn't very consistent, even if he does not want to hear it ... He was a big talent, but not every day. He was a very young player when he came from Eintracht Frankfurt to Mainz, a very skilled boy, very quick, a good striker." He was part of the Schalke squad that won the 1997 UEFA Cup.

In the mid-1990s, Wagner was one of several German-born players called up by United States men's national soccer team coach Steve Sampson due to their ancestry, along with Thomas Dooley and Michael Mason. Wagner made his debut in a friendly 3–1 win over El Salvador in Los Angeles on 30 August 1996, in which he was substituted at half-time for Brian McBride. He made five appearances the following year and two more in 1998, all but one as a starter. In April 1997, after Canada lost to the United States in a World Cup qualifying match in which Wagner played, the Canadian Soccer Association complained to FIFA that Wagner should be ineligible to play for the United States based on his appearances for Germany's youth teams. On 2 May 1997, FIFA announced that Wagner was eligible to play for the United States because his games with the German teams were exhibitions, not official matches. However, Wagner was rarely called into the U.S. team afterwards and he was not named to the squad for the 1998 FIFA World Cup.

Borussia Dortmund II

Following his playing career, Wagner became a manager, working mostly with his former 1. Mainz 05 teammate Jürgen Klopp. Wagner was appointed as Borussia Dortmund II manager with effect from 1 July 2011. He left the role on 31 October 2015, amid rumours that he was going to join Klopp's backroom staff at Liverpool.

Huddersfield Town

On 5 November 2015, Wagner was appointed manager of English club Huddersfield Town following the departure of Chris Powell. He brought Christoph Bühler, who had left Borussia Dortmund on 1 November 2015, with him as his assistant. In the summer of 2016, Wagner brought in 13 players from across the continent, including Danny Ward, Chris Löwe, and Aaron Mooy. He took his players on a bonding tour of Sweden, where they had to survive with only basic equipment for a few days. The team's success in the early 2016–17 season was largely accredited to the squad's tight bond, something that Wagner claimed was a direct result of this Sweden trip. A few weeks later, they visited Austria and kept two clean sheets in matches against Bundesliga teams Werder Bremen and Ingolstadt 04. After an unbeaten start to the 2016–17 season, Huddersfield were top of the table at the start of September, including a win at St James' Park against Newcastle United. Wagner was the EFL Championship Manager of the Month for August 2016 and February 2017. On 29 May 2017, Huddersfield secured promotion to the Premier League for the 2017–18…

In 2005, Wagner was best man at Jürgen Klopp's wedding. Wagner is married and has two daughters. His elder daughter, Lea Wagner (born 1994), is a sports journalist for German broadcaster ARD. In June 2023 she was appointed as a presenter of Sportschau.