At the beginning of each episode, webisode, and novel of Grimm there is a featured quote that often references the story, legend, etc. that the episode, webisode, or novel is based on. Sometimes the quote source plays a heavy role, while other times it plays a small role in the story of the episodes, etc. For episodes and webisodes, the background of the quote often features an item, location, or character that will appear. Most episodes have their own unique background for the quote. However, "Pilot" and "Love Sick" feature the same background while "Organ Grinder" features the same background as those two, but has different lighting. "Maiden Quest" and "Star-Crossed" also feature the same background as each other. "The Three Bad Wolves" and "Bad Moon Rising" feature the same background, but with different lighting. Every episode quote so far other than the one used in "One Angry Fuchsbau" is taken from the source of the story the episode is based on. The quote for "One Angry Fuchsbau" was made up by the episode's writer, Richard Hatem, although he drew inspiration from the tale used for the episode. The quote for "The Hour of Death" isn't from a real story, but from one that is featured in the episode. The quote for "Mishipeshu" is an original by the episode's writer, Alan DiFiore.
For several episodes in seasons 3 through 6, the episodes don't appear to be based on any preexisting literature. As such, quotes from such episodes are either taken from the words of well-known individuals (e.g., "Octopus Head" quoting Alexander Smith) or are taken from fairy tales previously adapted into episodes (e.g., "Revelation" using a quote from Hänsel and Gretel, a story previously utilized and adapted in "Organ Grinder").