The Viper's Bugloss (Hadena irregularis) is a species of moth of the family Noctuidae.

Meyrick describes it - Forewings whitish-ochreous, irregularly suffused with pale ochreous brownish; first and second lines edged externally with ochreous brownish, internally with dark brown; median line ochreous brown; orbicular and reniform outlined with pale; subterminal line pale, edged anteriorly with ochreous-brown; termen unmarked; cilia barred.

They have brownish lateral and dorsal lines and darker angled spots that open to the front of the dorsum.

In 1998 the United Kingdom government removed Hadena irregularis from schedule 5 (animals) of the Wildlife and Countryside Act, 1981 as it is believed to be extinct.

The cause of extinction has been hypothesised to be destruction of habitat, primarily the food source, which in the United Kingdom was limited to Spanish catchfly (Silene otites).