Catharina Wallenstedt, née Wallia (1627 – 1719) was a Swedish letter writer and courtier.

Composed of a collection of about 350 letters written between 1673 and 1718, mostly to her spouse and daughter Greta, they have been the object of research.

She was maid of honour to Queen Christina of Sweden in 1649–1655.

She was the mother-in-law to Nils Gyldenstolpe and Arvid Horn.

She was portrayed in the "Teckningar ur svenska adelns familjelif i gamla tider" by Ellen Fries (1895).