| Honorific-Prefix: | His Grace |
| Frederik Marcus Knuth | |
| Honorific-Suffix: | . |
| Office: | 1st Minister of Foreign Affairs of Denmark |
| Term Start: | 22 March 1848 |
| Term End: | 16 November 1848 |
| Predecessor: | Position established |
| Successor: | Adam Wilhelm Moltke, Count of Bregentved |
| Birth Date: | 11 January 1813 |
| Birth Place: | Christiania (Oslo), Norway, Denmark-Norway |
| Death Place: | Copenhagen, Denmark |
| Resting Place: | Sorø Old Cemetery, Sorø, Denmark |
| Alma Mater: | Copenhagen University |
| Parents: | Eggert Christopher Count Knuth Karen Rosenkrantz |
| Children: | 6, including: |
| Party: | Independent |
Frederik Marcus Knuth, 5th Count of Knuthenborg (11 January 1813 – 8 January 1856) was a Danish aristocrat, landowner, civil servant and politician.
A member of the Knuth family, he was educated at home and later at the University of Copenhagen. From 1847 to 1848 he served as amtmand in Sorø Amt. After the introduction of the constitutional monarchy in 1848, Knuth served as the first Minister of Foreign Affairs of Denmark from March to November 1848. From November 1848, he was member of The Danish Constituent Assembly (Danish: Den Grundlovgivende Rigsforsamling) as one of the members appointed by the king.
With the title of enfeoffed count (Danish: [[lensgreve]]), he was the fifth holder of the County of Knuthenborg on the island of Lolland from 1818 to 1856.[1]