Jacob Ulfeldt (1535 – 8 October 1593) was a Danish diplomat and member of the Privy Council from 1565.

He is mostly known for his very troubled diplomatic journey into Russia in 1578 during which he concluded an unfavourable treaty with Tsar Ivan IV (1530–1584) that brought him to disgrace at home.

However, his account of his Russian travels (published by Melchior Goldast in Latin during 1608) is still considered a main source of Danish-Russian relations as well as of 16th-century Russia.

He is mostly known for his very troubled diplomatic journey into Russia in 1578 during which he concluded an unfavourable treaty with Tsar Ivan IV (1530–1584) that brought him to disgrace at home.

[3] Ylfeldt's account of his Russian travels (published by Melchior Goldast in Latin during 1608) is still considered a main source of Danish-Russian relations as well as of 16th century Russia.