The acclaimed star, who appeared in Oscar-winning drama The Reader, passed away on Wednesday (25Jul12).
A lawyer for her family, who confirmed her death, did not provide information about the cause of her tragedy, according to The Hollywood Reporter.
Lothar received four best actress nominations at the German Film Awards, the country's version of the Oscars, winning the accolade in 1983.
Her screen credits also include the Academy Award-nominated drama The White Ribbon, which won the Palme d'Or at the Cannes Film Festival in 2009, and The Piano Teacher.
She also appeared alongside her actor husband Ulrich Muhe in the 1997 psychological thriller Funny Games. Muhe, who starred in the Oscar-winning movie The Lives Of Others, lost his battle with stomach cancer in 2007, aged 54.
Lohar was filming the drama Inner Amok with director Peter Brunner at the time of her death.