Xenocalamus transvaalensis is a species of venomous rear-fanged snake in the family Lamprophiidae. The species is endemic to Africa. There are no subspecies that are recognized as being valid.
X. transvaalensis is black dorsally, and white ventrally. Males may attain a total length (including tail) of 37 cm (14+1⁄2 in); females, 31.5 cm (12+3⁄8 in).
X. transvaalensis is found in Botswana, southern Mozambique, Republic of South Africa (former Northern Transvaal and former Zululand), and Zimbabwe.
In summer an adult female X. transvaalensis may lay two elongated eggs, 28 mm x 6 mm (1 1/16 in x 3/16 in).