Hypnale walli, or Wall's hump-nosed viper,[2] is a venomous pitviper species endemic to Sri Lanka.

The smallest member of its genus, it is distinguished by having a strongly upturned nose and lower scale counts.

[3] The specific name, walli, is in honor of Ceylonese-born British herpetologist Frank Wall.

In general, the color pattern is described as consisting of a series of 18–24 dorsolateral small subtriangular brown blotches, pointing upwards.

The type locality given is "Kanneliya Forest, Udugama Southern Province, Ceylon [Sri Lanka], elevation approximately 1,000 ft [300 m]".