Shadowmoor is an expansion set, codenamed "Jelly", from the trading card game Magic: The Gathering. It was released on May 2, 2008. The pre-release events for this set were held on April 19–20, 2008.

Shadowmoor is the first set of the Shadowmoor block, which started May 2008. Shadowmoor is the first large expansion to be released in a month other than October since Ice Age’s June 1995 release. The designers of the set are Mark Rosewater (lead), Sean Fletcher, Mark Gottlieb, Devin Low, and Ken Troop; the developers of the set are Aaron Forsythe (lead), Devin Low, Alexis Janson (the winner of The Great Designer Search Contest), Matt Place, Jake Theis, Steve Warner, and Doug Beyer. The Shadowmoor symbol might suggest a bat wing or dead leaf, but is a Jack-o'-lantern lid taken from the art of the card Reaper King, the King of the scarecrows, a prominent creature type in the set. The set's theme is color, utilizing hybrid (as seen in Ravnica) across the allied color pairs, along with innovations in hybrid mana. A new action is introduced in this set, called "Q", representing the untap symbol; according to Rosewater, this has "never [been] done before." Rosewater also stated that "the set plays into the duality theme between Lorwyn and Shadowmoor blocks, both in the art and the mechanics." For example, the same creature types from Lorwyn returned.