Jacob Mogensen, or Ebbe Ulfeldt (c. 1600 – c. 1670), was the brother of the Danish naval officer Corfits Ulfeldt who became a landscape painter in Delft.According to the RKD he was a registered pupil of Jacob Vosmaer. He is probably the "Delvenaar" referred to as "Ugaart", in Arnold Houbraken's Schouburg.