Jacob Ludwig Carl Grimm (1785-1863) and his brother Wilhelm Carl Grimm (1786-1859) are best known as the editors of Grimm's Fairy Tales, a massive collection of of over 200 legends, myths, and fairy tales.
Their father, a prosperous lawyer, died suddenly in 1796, bringing the brother's idyllic childhood to an abrupt end. They were brought up by an aunt, in reduced circumstances, and intended to study law. They both found themselves drawn to German medieval literature instead, and entered the University of Marburg. Jacob left before completing his degree, and went to Paris to assist his mentor with research. It was on his return home that Jacob and Willhelm began their search for traditional fairy tales. The first few are preserved in a series of letters from early 1808.
Wilhelm had a bad heart condition, and his health was too poor for him to work consistently. Jacob became a librarian to the new King of Westphalia in Cassel, and was paid well enough to support his brother, and enable them to indulge their interest in fairy tales. Although this was initially intended as part of a larger work on the history of German literature, it was the beginning of what was to become Wilhelm's life work: the constant expansion and editing of Kinder- und Hausmarchen (Children's and Household Tales, 1812).
With the fall of Napoleon, Jacob returned to Paris for a few years, and Wilhelm became the Cassel librarian. Jacob returned in 1816, and they both remained there until 1829.
Their huge publication output, including Ancient Danish Hero Songs, Lays and Tales in 1811, Children's and Household Tales in 1812 and 1815, Old German Forests in 1813, and Irish Folktales in 1826, brought them a huge amount of recognition in Germany. They were awarded honorary doctorates by Marburg, Berlin and Breslau.
Their other main work was a massive collaborative historical grammar and dictionary of the German language. (This was not completed for 100 years. By the time of William's death they had only reached the letter D. Jacob got no further than F.)
In recognition of their scholarship, they were both offered professorial posts at the University of Gottingen, but six years later were forced to resign when they refused to swear an oath of fealty to the state of Hanover.
The household moved to Berlin, along with Wilhelm's wife and three children. Jacob always remained a bachelor, and is described as the quieter, more single-minded and sad of the brothers.
The collection of fairy tales and folklore was closely tied to their belief in the importance of German culture, and the nation's literary history. But though they were keen to support the impression that the stories were raw transcriptions of traditional folklore, the brothers were retellers and rewriters, who polished the stories carefully before publication. John M. Ellis, for example, argues that most of the tales were collected from middle class friends and neighbours rather than the old peasant women they seemed to revere. The first edition in particular shows a great deal of rewriting - they "gave the texts...a much more elaborate verbal structure", adding "language intended to clarify motivation and explain the events more thoroughly." This was nothing out of the ordinary - style and content was held to be more important than accuracy of transmission - but it goes contrary to the professed methods of the editors. They are still regarded as the founders of the modern study of folklore.
Also, there was a twofold leakage from written sources: many of the stories the Grimms were told had originated in Charles Perrault's popular volume, and then retold to them by their literate, French-speaking friends. Later on, other folklorists and collectors realised that many of the seemingly traditional tales they were hearing in Eastern Europe had been assimilated into oral culture from the cheap, widely distributed copies of the Grimms' books.
Their fairy tales do not seem to have been initially intended for children or non-scholarly readers. The first edition had copious notes, a long introduction and no illustrations. It was only after the first English translation appeared, illustrated by George Cruickshank that they selected about fifty of the most popular tales, re-edited them to soften some of the more violent edges, and republished a cheap edition designed for young readers.