Tranquillo Barnetta (born 22 May 1985 in St. Gallen) is a Swiss footballer who plays as a midfielder for Schalke 04 and the Swiss national team. He usually plays out wide as a left winger but can also play in a more withdrawn role as a defensive midfielder. Barnetta is known for his "extreme pace, mobility and creativity."

Club
Barnetta started his career with St. Gallen in his hometown but was soon snapped up by German side Bayer Leverkusen in January 2004 During his first season at Bayer, he had a loan spell at Hannover 96, returning to Bayer in March 2005.

After a good showing at the World Cup in Germany, Barnetta became a regular in the Bayer squad. The 2008–09 season was one to forget for him, after Bayer finished two places lower than the previous season and his goals tally dropped slightly. During the summer transfer window, he was linked with a move away from Bayer as his place in the squad seemed under threat from loanee Toni Kroos. He regained his good form in the 2009–10 season, scoring a brace in only his second league game of the season and contributing to Bayer's unbeaten run for the entire first half of the season.

On 2 July 2012, after his contract ran out at Bayer Leverkusen, Barnetta signed a three year deal with Bundesliga rivals Schalke 04 in preparation for the Gelsenkirchen club's participation in the Champions League.

International
Barnetta is a former youth international and was in the Swiss U-17 squad that won the 2002 U-17 European Championships along with future senior teammates Philippe Senderos and Reto Ziegler. He has been a member of the senior national team and was first called up to the squad for the Euro 2004 but did not make an appearance. At the 2006 World Cup, he scored the second goal in Switzerland's group stage win over Togo, but missed a penalty kick in the shootout against Ukraine, which Switzerland lost 3–0. On 4 July, Barnetta was shortlisted for the tournament's Best Young Player award. He was ever present in 2010 World Cup qualifying as the Swiss secured a place by finishing top of their group. On 4 June 2011, Barnetta scored two free kicks in quick succession against England in the Euro 2012 qualifiers.