Reinhold Rücker Angerstein (October 25, 1718, at Vikmanshyttan – January 5, 1760, in Stockholm) was a Swedish metallurgist, civil servant and entrepreneur.
At the age of 31 he started a series of long journeys abroad, financed by the Swedish Association of Iron Masters (Jernkontoret).
Between 1749 and 1757 he was constantly travelling, with only few short spells in Sweden: in Germany, Austria, Italy, France, Portugal, Belgium, the Netherlands and Britain.
Towards the end of his life he purchased the Vira Iron Works in Uppland in 1757, northeast of Stockholm, renowned for forging of weapons for the army.
His visit to Sheffield was brief, less than a day, and it has been suggested that he was driven out of the town for showing too much interest in the crucible process newly invented by Benjamin Huntsman.