William O'Grady (b. 1952) is Professor of Linguistics at the University of Hawai'i at Mānoa and the clearest theorist of emergentist syntax working from outside the usage-based mainstream. His work takes seriously the project of explaining grammatical structure without innate UG, but does so through a different route from Tomasello or Nick Ellis: a linear, efficiency-driven processor whose primary job is reducing the load on working memory.
Syntactic Carpentry (2005, Erlbaum) is the book-length statement. It takes core syntactic phenomena — phrase structure, co-reference, control, agreement, contraction, extraction — and shows how each falls out of incremental processing constraints rather than principles of an innate language faculty. O'Grady has extended this programme to first-language acquisition, heritage-language development, and Koreanic languages, and his co-edited Handbook of Second Language Acquisition and introductory Contemporary Linguistics textbook have given the emergentist position a visible teaching platform.