the Regenstein family, also Reinstein, was a Lower Saxon noble family, which was named after the eponymous Regenstein Castle near Blankenburg on the edge of the Harz Mountains of central Germany.
In 1162 Cunradus Comes de Regenstein (Conrad, Count of Regenstein), the son of Count Poppo I of Blankenburg from the House of Reginbodonen, was documented for the first time by name, thus establishing the line of Reinstein-Blankenburg. Heimburg came into their possession in the 14th century as a fief and founded the Younger Line of Reinstein(-Heimburg). Regenstein Castle (the line of Reinstein-Reinstein) was abandoned in the mid-15th century in favour of Blankenburg and Derenburg. The last male descendant of the noble family, John Ernest, Count of Regenstein, died in 1599. Parts of the county evolved into the Principality of Blankenburg.
The coat of arms of the comital line displays in silver a (black) red, six-tined antler. The later quartered shield shows also in silver (1:4) a black and in (2:3) a red six-tined antler. Helmet: crowned, right a black six-tined antler, left a red one of the same. The mantle is black and silver on the right and red and silver on the left.