The Monsanto Company ( ) is a multinational agricultural biotechnology corporation. It is the world's leading producer of the herbicide glyphosate, marketed as "Roundup". Monsanto is also by far the leading producer of genetically engineered (GE) seed, holding 70%–100% market share for various crops. Agracetus, owned by Monsanto, exclusively produces Roundup Ready soybean seed for the commercial market. In March 2005, it finalized the purchase of Seminis Inc, making it also the largest conventional seed company in the world. It has over 16,000 employees worldwide, and an annual revenue of US$7.344 billion reported for 2006.

Monsanto's development and marketing of genetically engineered seed and bovine growth hormone, as well as its aggressive litigation and political lobbying practices, have made the company controversial around the world and a primary target of the anti-globalization movement and environmental activists. While other chemical and biotech multinationals face similar criticisms, Monsanto tends to be targeted more routinely and more strongly.