This is just so cool. Video of Solenodon paradoxus, or the Hispaniolan Solenodon, from the jungle of the Dominican Republic. S. paradoxus and S. cubanis (from Cuba) are the only mammals known that can inject venom through specialised teeth.
While no other known living mammal can inject venom in this way, a number of fossil mammals have similarly modified teeth, and so it is though that this ability may have been more widespread in the geological past.
The animal is very rare - although if you looked like an old man with a bad toupee, you'd be reclusive too!
More info in the BBC story that accompanies the video.