Any of various animals that have red eyes. • The common rudd (Scardinius erythrophthalmus), a freshwater fish. • Any of various grass-skippers or hesperiid butterflies of the genus Matapa. • The red-eyed treefrog (Agalychnis callidryas), which is native to neotropical rainforests. • A species of cicada, Psaltoda moerens, native to eastern Australia. • The red-eyed vireo (Vireo olivaceus), a small American songbird. • Any of various round herrings of the genus Etrumeus. • Either of two subspecies of the copperhead (Agkistrodon contortrix), a venomous pit viper native to the United States: either the broad-banded copperhead or Texas copperhead (Agkistrodon contortrix laticinctus), or the highland moccasin or northern copperhead (Agkistrodon contortrix mokasen). • Any of various sunfishes of the family Centrarchidae, especially the redeye bass (Micropterus coosae) or the rock bass (Ambloplites rupestris). • The redeye tetra (Moenkhausia sanctaefilomenae), a freshwater fish, commonly kept in aquariums, native to South America. • Types of beverages or sauces. • A drink made by adding a shot of espresso to a cup of coffee. • A drink consisting of beer with tomato juice. • A strong but poor-quality whiskey. • Ellipsis of red-eye gravy. • An overnight airplane flight or train trip. • Redness of the conjunctiva; especially when caused by conjunctivitis (pinkeye). • Redness in the eye(s) of someone in a colour photograph, as an unwanted consequence of light from a flash reflecting off blood vessels in the retina.