Gyllenhaal is a Swedish noble family descended from the cavalry Lieutenant Nils Gunnarsson Haal (d. 1680 or 1681), ennobled in 1652 with a change of surname to Gyllenhaal. Some notable members of this family are:

Nils Gunnarsson Gyllenhaal's descendants today stem from two of his sons; Lars Gyllenhaal b. 1645 d. 1710, Lieutenant of the Vestgotha cavalry regiment, and his younger brother Hans Gyllenhaal b. 1655 d. 1710. Hans was killed in action at the battle of Helsingborg as a cavalry captain.

The members of the older branch descending from Lars are still living in Sweden. The most notable member of that branch is the above mentioned Prime Minister for Justice Lars Herman Gyllenhaal. In 1851 he was created Knight and Commander of the Royal Order of the Seraphim. His great-great grandson Herman Gyllenhaal till Haerlingstorp b. 1934, is now the baron of the family and his son, the above-mentioned Lars Gyllenhaal, is now the head of both branches of the noble family Gyllenhaal.

All the members of the family in the USA are descending from Hans Gyllenhaal and come from his great great-great grandson Anders Leonard b.1842 d. 1905, who in 1866 immigrated to the USA, and his wife Amanda b. Nelson b.1859 d.1948. The hitherto most memorable member of this younger branch was the above-mentioned *Leonard Gyllenhaal (1752-1840). He was in 1807 created a Knight of the Royal Order of Vasa for his scientific works as an entomologist and his scientific work about Swedish insects, Insecta Suecia descripta.

Jacob Benjamin "Jake" Gyllenhaal ( /ˈdʒɪlənhɔːl/ JIL-ən-hawl; born December 19, 1980) is an American actor. The son of director Stephen Gyllenhaal and screenwriter Naomi Foner, Gyllenhaal began acting at the age of ten. Following his first lead role in 1999's October Sky, he starred in the indie cult hit Donnie Darko (2001), in which he played a psychologically troubled teenager alongside his older sister, actress Maggie Gyllenhaal. In 2004 he appeared in the science-fiction film The Day After Tomorrow, portraying a student caught in a cataclysmic global cooling event. He then played against type as a frustrated Marine in Jarhead (2005). The same year his role as Jack Twist in Brokeback Mountain earned him critical acclaim and an Academy Award nomination for Best Supporting Actor. He has since played the lead roles in many notable films, including Zodiac (2007), Prince of Persia: The Sands of Time (2010) and Source Code (2011).

Gyllenhaal has promoted various political and social causes. He has appeared in Rock the Vote advertising, campaigned for the Democratic Party in the 2004 U.S. presidential election, promoted environmental causes, and campaigned on behalf of the American Civil Liberties Union.