Johan Fredrik Lilljekvist was a Swedish architect. He is best known for his controversial restoration of Gripsholm Castle and as the architect of the new building for the Royal Dramatic Theatre in Stockholm.

Gripsholm Castle is a castle in Mariefred, Södermanland, Sweden. It is located by lake Mälaren in south central Sweden, in the municipality of Strängnäs, about 60 km west of Stockholm. Since Gustav Vasa, Gripsholm has belonged to the Swedish Royal Family and was used as one of their residences until the 18th century. It is now a museum, but is still considered to be a palace at the disposal of the King and as such it is part of the Crown palaces in Sweden.