Frithjof Møinichen Plahte (8 February 1836 – 17 July 1899) was a Norwegian merchant and landowner.
After a career in the timber business, he settled in Bærum where he invested in business and in several farms.
His family socialized within the upper echelon in the capital city region, and he stood behind the establishment of Høvik Church and the use of Fleskum farm by a group of painters.