Vishpala (viśpálā) is a woman (alternatively, a horse) mentioned in the Rigveda (RV 1.112, 116, 117, 118 and RV 10.39). The name is likely from viś "settlement, village" and bala "strong", meaning something like "protecting the settlement".
Vishpala is helped in battle (alternative, in the prize-race) by the Ashvins. As she lost her leg "in the time of night, in Khela's battle" (alternatively, "in Khela's race, eager for a decision"), they gave her a "leg of iron" so that she could keep running (1.116.15).
As is often the case in the Rigveda, especially in the young books 1 and 10 (dated to roughly 1000 BC) a myth is only alluded to, the poet taking for granted his audience's being familiar with it, and beyond the fact that the Ashvins gave Vishpala a new leg, no information has survived, neither about Vishpala herself nor about "Khela's battle", or indeed the character of Khela (the name meaning "shaking, trembling").
Nevertheless, the allusion qualifies as the earliest reference to the concept of a prosthesis, while in Sayana's interpretation it can also be taken as an early reference to a female warrior.