Neuer has been injured since September, when he suffered a fractured foot, and has made just four appearances since last April.
Manager Joachim Low has, however, included the Bayern Munich goalkeeper in his provisional squad, along with Barcelona's Marc-Andre ter Stegen, Bayer Leverkusen's Bernd Leno and PSG stopper Kevin Trapp.
Low has confirmed that the intention is to test Neuer's fitness ahead of the tournament starting, telling reporters: "We want to see for ourselves if Manuel Neuer is fit, we have a chance to see and assess him. And after the training camp we want to talk fair and square."
Reus, meanwhile, appears to finally have a chance to play in a World Cup, having returned to form and fitness at Borussia Dortmund since his comeback from injury in February.
The winger missed the 2014 tournament in Brazil, despite being named in the initial squad, after sustaining an ankle injury in the team's warm-up win over Armenia.
His club-mate Gotze, who scored the winning goal in the final as Germany triumphed four years ago, misses out, however, after struggling for fitness and form at Signal Iduna Park this term.
Mario Gomez could add to his 73 caps in Russia, having previously played in Euro 2008, the 2010 World Cup, Euro 2012 and Euro 2016. However, he missed out on playing in the 2014 World Cup due to an injury-hit season.
Seemingly as a result of Gomez's inclusion Sandro Wagner misses out, despite an impressive season at Bayern Munich. The 30-year-old has scored 15 goals and provided six assists in 34 appearances for the Bavarian giants thus far this term, and has also netted five goals for Germany in just eight caps.
However, Low has opted against calling him up for the tournament, instead selecting the likes of Thomas Muller, Gomez, Timo Werner and Nils Petersen.
Arsenal centre-back Shkodran Mustafi is not included though, while Emre Can, who has been struggling with a back injury, is another name from England's top flight that failed to make the squad.