Ichthyology

• Long-tailed river stingray, freshwater stingray
• Long-tailed thresher shark, thresher shark inhabiting tropical and temperate waters worldwide

Mammology

• Greater Long-tailed Hamster, major crop-eating rodent that resides in Northern China
• Little Long-tailed Dunnart, dunnart that was described in 1984
• Long-tailed Climbing Mouse, Rhipidomys mastacalis, rodent species from South America
• Long-tailed Climbing Mouse, Vandeleuria, rodent genus
• Long-tailed Dunnart, Australian dunnart that has a tail longer than its body
• Long-tailed Mouse, native Australian rodent
• Long-tailed Planigale, the smallest of all marsupials
• Long-tailed Pygmy Possum, diprotodont marsupial found in the rainforests of northern Australia, Indonesia and New Guinea
• Long-tailed Shrew, small North American shrew found in Atlantic Canada and the north-eastern United States
• Long-tailed Spiny Rat, spiny rat species from South America
• Long-tailed Tree Rat, spiny rat species from South America
• Long-tailed Vole, small vole found in western North America
• Long-tailed Weasel, the most widely distributed mustelid in the New World
• New Zealand Long-tailed Bat, aerial insectivore
• Nicobar Long-tailed Macaque, subspecies of the Crab-eating Macaque

Ornithology

• Long-tailed Broadbill, species of broadbill that is found in the Himalayas, Southeast Asia, and Indonesia
• Long-tailed Cormorant, member of the cormorant family of seabirds
• Long-tailed Duck, medium-sized sea duck
• Long-tailed Glossy Starling, member of the starling family of birds
• Long-tailed Hawk, bird of prey in the family Accipitridae
• Long-tailed Hermit, large hummingbird that is a resident breeder in Venezuela, the Guianas, and northern Brazil
• Long-tailed Paradigalla, large black bird of paradise
• Long-tailed Parakeet, parrot of Southeast Asia
• Long-tailed Shrike, member of the bird family Laniidae
• Long-tailed Silky-flycatcher, passerine bird which occurs only in the mountains of Costa Rica and western Panama
• Long-tailed Skua, seabird in the skua family Stercorariidae
• Long-tailed Tit, very small passerine bird
• Long-tailed tits, group of small passerine birds with medium to long tails

Other

• Long-tailed pair, common design in electronics for implementing a differential amplifier
• Long-tailed Skipper, spread-winged skipper butterfly found throughout tropical America and into the southern part of the United States