Things connected with equid mules

• 40 acres and a mule, compensation to be awarded to freed slaves after the American Civil War
• Twenty-mule team, a team of eighteen mules and two horses, used for hauling very large wagons in Death Valley in the 19th century

Other hybrids

• Mule (bird), captive-bred hybrids of finch species such as goldfinch and canary
• Mule (sheep), in British sheep farming, a cross between a meat ram and a hardy mountain ewe
• Development mule, a vehicle equipped with experimental or prototype components for testing
• Mule (coin), a coin or medal minted with obverse and reverse designs not normally seen on the same piece

Other animals

• Mule deer (Odocoileus hemionus), a North American species of deer (not a hybrid) with large mule-like ears