Oskar Groening, defendant and former Nazi SS officer dubbed the "bookkeeper of Auschwitz", is pictured in the courtroom during his trial in Lueneburg, Germany, July 15, 2015.
Groening's lawyer, Hans Holterman, told German public broadcaster NDR, that the former Nazi died last week.
The former SS guard said during his trial that he oversaw the collection of belongings from those killed at Auschwitz or used as slave labour.
There were several occasions when he was assigned to "ramp duty", which involved processing new arrivals.
Oskar Groening was convicted in Lueneburg in 2015 as an accessory to the murder of 300,000 Jews.
A court doctor determined a year ago that he was able to serve his sentence, on condition he was given appropriate nursing and medical care, but he was never jailed. The 96-year-old Groening's death first was reported Monday by German weekly Der Spiegel.
One million European Jews were slaughtered in Auschwitz, only a sixth of the number who died as part of the Nazi regime overall.
He was sentenced not for atrocities he was known to have committed, but on the basis that he served at the Sobibor camp in occupied Poland - for having been a cog in the Nazis' killing machine.
Groening was only the third person to be convicted as an accessory to Nazi murders.
He said he was "very sorry" for his actions.
"The essential, nearly frightening, point about Oskar Groening is that he is one of the least exceptional human beings you are ever likely to meet", said author Laurence Rees, who interviewed Groening in 2005.