Wallace began publishing fiction in 1997, when he launched Cosmos Books, with Philip J. Harbottle, and released Fantasy Annual, a paperback magazine of British authors including E.C. Tubb, John Russell Fearn, and Sydney Bounds. In 1999, the Cosmos Books name was licensed to Wildside Press and output greatly increased, expanding with American and Australian authors. He also became a freelance editor for Wildside Press, working from Ohio. In mid-2001, Wallace stepped in to assist an ailing company, Imaginary Worlds, though it soon went into bankruptcy. Wallace then launched Prime Books to publish a few of the orphaned books, including the award-winning City of Saints and Madmen, by Jeff VanderMeer. Later, in 2003, he licensed the company to Wildside Press, and moved from Ohio to Pennsylvania, as a full-time senior editor. In early 2009, Wallace reacquired Prime Books, and relaunched it as an independent publishing house in May that year. Wallace was twice-nominated for a World Fantasy Award in 2003 and 2004 for editing Prime Books, in the and categories. Around this time, he felt that there was a lack of short fiction available in the literary fantasy genre and to cater to this, he launched Fantasy Magazine in 2005, at the World Fantasy Convention in Wisconsin. During 2006 his first nationally distributed book, Horror: The Best of the Year was released, and he took on a co-editing job with Nick Mamatas, with Clarkesworld Magazine. That same year, he won the World Fantasy Award in the category for editing Prime Books. In 2009, his work for Clarkesworld gained recognition with Hugo Award and World Fantasy Award nominations. In 2010 and 2011, those efforts were rewarded with back-to-back Hugo Awards. Sean and the rest of the Clarkesworld team also received World Fantasy Award nominations in 2010, 2012, and 2014. In 2011 he served as a World Fantasy Awards judge and in the same year he launched the World SF Travel Fund with Lavie Tidhar. In 2013 Clarkesworld Magazine and its staff garnered yet another Hugo Award nomination for their work, winning it yet again for their third time. in 2014 the magazine currently garnered yet another World Fantasy Award nomination and this time the magazine won its first World Fantasy Award. Other genre efforts he's been involved with include the relaunch and management of WSFA Press; co-founding the Shirley Jackson Awards; and managing the SFWA Book Depot at the Nebula Awards conference. He currently resides in Germantown, Maryland with his wife, Jennifer, and their two daughters, Cordelia and Natalie.
Works
The Mammoth Book series
The Mammoth Book of Steampunk
The Mammoth Book of Steampunk Adventures
The Mammoth Book of Warriors and Wizardry
The Mammoth Book of Dieselpunk
The Mammoth Book of Kaiju
The Realms/Clarkesworld series
Realms: The First Year of Clarkesworld Magazine, with Neil Clarke and Nick Mamatas
Realms: The Second Year of Clarkesworld Magazine, with Neil Clarke and Nick Mamatas
Clarkesworld: Year Three, with Neil Clarke and Nick Mamatas