Elsevier (Dutch: [ˈɛlzəviːr]) is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as The Lancet, Cell, the ScienceDirect collection of electronic journals, Trends, the Current Opinion series, the online citation database Scopus, the SciVal tool for measuring research performance, the ClinicalKey search engine for clinicians, and the ClinicalPath evidence-based cancer care service. Elsevier's products and services include digital tools for data management, instruction, research analytics, and assessment.

Elsevier is part of the RELX Group, known until 2015 as Reed Elsevier, a publicly-traded company. According to RELX reports, in 2021 Elsevier published more than 600,000 articles annually in over 2,700 journals; as of 2018 its archives contained over 17 million documents and 40,000 e-books, with over one billion annual downloads.

Researchers have criticized Elsevier for its high profit margins and copyright practices. The company earned £942 million in profit with an adjusted operating margin of 37% in 2018. Much of the research that Elsevier publishes is publicly funded; its high costs have led to accusations of rent-seeking, boycotts, and the rise of alternate avenues for publication and access, such as preprint servers and shadow libraries.