Physicians that saw those with the Bubonic Plague during the Venetian Renaissance, often known as Plague Doctors, wore a bird-like mask for protection and to depict the symbol of the Plague, the raven.
They didn't do it just to be unbelievably creepy, though. The costumes were as much protective as they were scary-looking. The Bubonic Plague was extremely contagious and deadly. The overcoat was made of extremely heavy fabric that allowed for extra protection. The mask actually had glass eyes to prevent the infection getting in through the eyes.
The beak, arguably the creepiest part of the mask, also had a good functional reason. In the past, before germs and bacteria were discovered, it was thought that diseases were carried through a bad air that emanated from the diseased. The Bubonic Plague was very contagious, so the beak served as an extra protection from it. The beak was filled with scented materials, such as amber, balm-mint leaves and rose petals.
Finally, the wooden cane was a pointer that was useful for examining the patients without having to touch them. An interesting fact is that these plague doctors were actually considered to be second-rate doctors that didn't have the expertise to put their own practice, and as a result, had to take on these riskier patients.