Halting State is a novel by Charles Stross, published in the United States on 2 October 2007 and in the United Kingdom in January 2008. Stross has said that it is "a thriller set in the software houses that write multiplayer games". The plot centres on a bank robbery in a virtual world. It features speculative technologies, including Specs and virtual server networks over mobile phones. The book is on its second printing in the United States. The novel was nominated for both the Hugo and Locus Awards in 2008.

The main story is split between three main protagonists, Sue, Elaine, and Jack, whose sections are always in the second person, with italicised thoughts in first person during each character's respective chapter. Each chapter is followed in sequential trilogies (Sue, Elaine, Jack) for the duration of the novel. This pattern excepts only the prologue and epilogue of the novel, which both contain faux email to supporting characters.

A sequel to Halting State entitled Rule 34 (previously '419') was released in mid-2011.