Were Karl Marx and Leopold II of Belgium alive at the same time?
Yes. Karl Marx and Leopold II of Belgium were alive at the same time for 47 years, from 1835 to 1883.
Karl Marx was 16 when Leopold II of Belgium was born.
Leopold II of Belgium was 47 when Karl Marx died, aged 64.
Leopold II of Belgium
King of the Belgians from 1865 to 1909
Born 9 April 1835 · died 17 December 1909, aged 74