Hydrox is the brand name for a cream-filled chocolate sandwich cookie manufactured by Leaf Brands. It debuted in the United States in 1908, and was manufactured by Sunshine Biscuits for over 90 years. Hydrox was largely discontinued in 1999 three years after Sunshine was acquired by Keebler, which was later acquired by Kellogg's. In September 2015, the product was re-introduced by Leaf Brands.

The similar Oreo cookie, introduced in 1912, is a replica of the original Hydrox. The Oreo eventually exceeded Hydrox in popularity, which resulted in the Hydrox being perceived as an Oreo off brand. Compared to Oreos, Hydrox cookies have a sweeter filling and a crunchier cookie shell that has been noted to become less soggy in milk.