Solenodons look similar to very large shrews. They both have venomous bites; the venom is delivered from modified salivary glands via grooves in their second lower incisors.
Platypus (Ornithorhyncus anatinus)
Males have a venomous spur on their hind legs. Echidnas, the other monotremes, have spurs but no functional venom glands.
Male Playpuses have small spurs on the back of their front heels that secrete a mild venom. Even though it isn't fatal to humans, it has been known to cause much pain to those that are unlucky.