Field Marshal count Augustin Ehrensvärd (25 September 1710 – 4 October 1772) was a Swedish military officer, military architect, artist, creator of the Suomenlinna (Sveaborg) fortress, Svartholm fortress and the Swedish archipelago fleet.

Ehrensvärd's design was a low-profile bastion-type fortress that would follow the natural contours of the islands and thus remain inconspicuous to enemy fleets.

In addition to architecture, Ehrensvärd's interests included painting, educational psychology and botany.

He was also well respected by the Finnish people, who appreciated his efforts in the construction of Sveaborg, an important cultural and economic centre in the eastern part of 18th-century Sweden, which later would become modern Finland.

Ehrensvärd's burial monument in Sveaborg was designed by king Gustav III of Sweden himself.