This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Dipsa (Medieval Bestiaries)
Dipsa is a tiny, mucus-like, extremely venomous snake from Medieval bestiaries. They were so venomous that their victim would die before becoming aware he had been bitten. The victim of the dipsa has no time to feel horror at his fate. Aelian points out that the dipsas is white with two black stripes on its tail; Topsell mentions its black tail and black-and-yellow spots on its anterior; Aldrovandi pictures it with longitudinal black and white stripes and prominent scales on its head.
The small size of the dipsas makes it easy to overlook, and its bite is painless; its victims often are oblivious to the cause of their unnatural thirst. The venom seeps into the bones, sets fire to the organs, absorbs vital fluids, and parches the tongue and throat. Sometimes victims are driven to drink so much that their stomachs explode; if there is no water around, they eventually succumb to internal burning.