The Cocos tyrannulet (Nesotriccus ridgwayi), also known as the Cocos flycatcher, is a species of bird in the tyrant flycatcher family Tyrannidae. It is a small (13 cm) grey bird with a long bill.
It is endemic to Cocos Island off Costa Rica. Its natural habitats are subtropical or tropical moist lowland forest, subtropical or tropical swamps, subtropical or tropical moist montane forest, and subtropical or tropical moist shrubland.
It is thought to be threatened by introduced species, particularly rats and feral cats, which prey on the species, and pigs which destroy habitat through foraging. There is no evidence yet of a decline, but is listed as Vulnerable due to its tiny range.