That's Heinrich XI
of the Reuss Elder Line
, Count Reuss zu Obergreiz, and from 1778 Prince Reuss [zu Greiz] when he was made a Prince of the Empire.
Born 18 March 1722; succeeded his 4 year-old brother Heinrich IX in Obergreiz 17 March 1723; died 28 June 1800.
> Reigned 77 years, 3 months and 11 days.