Loris Sven Karius (born 22 June 1993) is a German professional footballer who plays as a goalkeeper for 2. Bundesliga club Schalke 04. He represented Germany at youth level.

Karius began his career with VfB Stuttgart before moving to Manchester City in 2009. After two years in Manchester City's youth system, he returned to Germany with Mainz 05. He established himself as the first-choice goalkeeper for the Bundesliga side before transferring to Liverpool in 2016 for a fee of £4.75 million. Karius would go on to play in the 2018 UEFA Champions League final with the club, with Liverpool suffering a 3–1 defeat to Real Madrid and Karius making two crucial goalkeeping errors that led to goals. He was subsequently loaned out to Beşiktaş and Union Berlin before later joining Newcastle United and Schalke.

Karius was born in Biberach, Baden-Württemberg to Christine and Harald Karius. Harald intended for his son to become a motocross rider, but Loris' grandfather, Karl, encouraged him to focus on football.

Karius attended Pestalozzi-Gymnasium Biberach until his move to England in 2009 where he was then privately tutored.

Karius played for local team SG Mettenberg and SSV Ulm before joining VfB Stuttgart, where he rose through the youth ranks and appeared for the German under-16 national team against FYROM in September 2008. Manchester City invited Karius and his family to England after watching him in Germany's under-16 game against Azerbaijan, and completed his signing on 1 July 2009. Karius played for the under-18 and the under-21 Manchester City teams, but did not make a senior appearance during his time in Manchester.

He was loaned to Mainz 05 in August 2011, where he played for Mainz 05's reserve team, Mainz 05 II, in the Regionalliga. On 11 January 2012, the move was made permanent with Karius committing himself to a two-year deal with an option for a third year that would extend his contract to June 2015. He made his Mainz 05 debut on 1 December 2012 in a Bundesliga match against Hannover 96 when he was substituted for Shawn Parker after goalkeeper Christian Wetklo had been sent off, which, aged 19 years and 5 months, made Karius the youngest goalkeeper ever to play in the Bundesliga for Mainz. He made no further appearances in the 2012–13 season, but established himself as first-choice goalkeeper in the 2013–14 season and on 12 January 2015 signed a three-year contract extension. Karius was ever-present in the 2015–16 season, keeping nine clean sheets, saving two penalties and being voted the second-best goalkeeper in the league in a poll of 235 fellow Bundesliga players, ranking behind only Manuel Neuer.

On 24 May 2016, Karius signed with Liverpool for a fee of £4.75 million on a five-year deal. He was given the number 1 shirt.

Karius made his Liverpool debut in a 3–0 League Cup win over Derby County on 20 September 2016. He played his first Premier League match against Hull City, which ended in a 5–1 victory for the Reds, on 24 September. Karius recorded his first Premier League clean sheet on 17 October, in a 0–0 draw with rivals Manchester United. On 24 October 2016, Jürgen Klopp confirmed that Karius was Liverpool's first-choice goalkeeper, ahead of Simon Mignolet. After two sub-par performances in early December, which included spilling Lewis Cook's tame shot into the path of Nathan Aké to tap home into an empty net to give Bournemouth a 4–3 win, Karius was dropped from the starting eleven. Regarding this decision, Klopp stated he wanted to take Karius "out the firing line," and that "Karius is a young goalkeeper. He will bounce back."