L. Timmel Duchamp is the author of the five-volume Marq'ssan Cycle, which won a special Tiptree Award honor in 2009, and the founder and publisher of Aqueduct Press. She has published two collections of short fiction: Love's Body, Dancing in Time (2004), which was shortlisted for the Tiptree and includes the Sturgeon-finalist story "Dance at the Edge," the Sidewise Award-nominated "The Heloise Archive," and the Titpree-shortlisted "The Apprenticeship of Isabetta di Pietro Cavazzi"; and Never at Home, which includes a 2011 Tiptree-Honor List story, and co-author, with Maureen McHugh, of a mini-collection, Plugged In, published in conjunction with the authors' being GoHs at WisCon. Her Marq'ssan Cycle consists of Alanya to Alanya (2005), Renegade (2006), Tsunami (2007), Blood in the Fruit (2007), and Stretto (2008). Her novel The Waterdancer's World appeared in 2016; another novel, Chercher la Femme, appeared in 2018 and was on the 2018 Otherwise Award Honor List; her short novel, The Red Rose Rages (Bleeding) appeared in 2005. She has also published the novellas De Secretis Mulierum and The Silences of Ararat, as well as dozens more short stories and novellas, including "Motherhood, Etc" (short-listed for the Tiptree) and "Living Trust" (Nebula and Homer Award finalist). In addition to her fiction, she has published a good deal of nonfiction. Since 2011 she has been the Features Editor of The Cascadia Subduction Zone. She was also the editor of Talking Back: Epistolary Fantasies (2006), The WisCon Chronicles, Vol. 1 (2007), Narrative Power: Encounters, Celebrations, Struggles (2010), Missing Links and Secret Histories: A Selection of Wikipedia Entries from across the Known Multiverse (2013), and co-editor, with Eileen Gunn, of The WisCon Chronicles, Vol. 2: Provocative essays on feminism, race, revolution, and the future (2008). Her latest book is Like Shards of Rainbow Frolicking in the Air (2025), a collection of short fiction.

In 2008 she appeared as a Guest of Honor at WisCon. In 2009-2010 she was awarded the Neil Clark Special Achievement Award ("recognizing individuals who are proactive behind the scenes but whose efforts often don't receive the measure of public recognition they deserve"). In 2015 she was the Editor Guest at Armadillocon. She has been a finalist for the World Fantasy Award twice, for her work as a publisher and editor. She has taught at the Clarion West Writers Workshop and has taught one-day Clarion West workshops. She lives in Seattle.