Dan Vesterby Thomassen (born 24 March 1981) is a Danish former professional footballer and current assistant coach of club Sampdoria. He has played for Danish Superliga side AGF Aarhus, Norwegian side VÃÂ¥lerenga and Danish champions Copenhagen and Italian side Padova.
In his youth, he started playing for IHF Aarhus and later on transferred to AGF. He moved to the Italian club Calcio Padova at the age of 17, and in 2004, he signed a three-year contract with FCK.
In July 2007, he signed for VÃÂ¥lerenga. After one season in Norway, he moved back to his home city to play for AGF.
Shortly after signing with AGF in 2008, he suffered a serious knee injury, which meant he missed a large part of the season.
He moved back to Italy in 2011 to finish his playing career and retired in 2018.
After retiring from active football, Thomassen took up a career as a youth coach, joining Vicenza and covering various training roles, being appointed head coach of the Under-19 team in 2022.
On 16 March 2023, following the dismissal of Francesco Modesto, he was promoted to head coach of Vicenza in the Serie C league for the remainder of the season. Just a month later, on 11 April 2023, he guided Vicenza to win the Coppa Italia Serie C after defeating Juventus F.C. Next Gen in a two-legged final.
In July 2023, Thomassen was announced as the new assistant coach of Brescia, working alongside head coach Daniele Gastaldello. Both Gastaldello and Thomassen were dismissed from their roles on 10 November 2023, following a negative string of results in the Serie B league.
In March 2024, following the appointment of Luca Gotti in charge of Serie A relegation-fighting club Lecce, Thomassen joined the Giallorossi from Salento as their new assistant coach. They managed to keep the club in Serie A for the following season. He left later that year after Gotti was dismissed from his role.
On 26 March 2026, Sampdoria announced the hiring of Thomassen as Attilio Lombardo's new assistant coach.