I have a special love for this family of flies, who are all voracious, energetic predators (both as larvae and adults) and who all look like grumpy Muppet hobos.
Robber flies in general tend to be large, with long legs, a long, tapered abdomen and a big, fluffy “beard” obscuring some pretty serious mouthparts. They catch prey — including big, fast-moving things like dragonflies — on the wing and inject them with paralytics and enzymes to render their insides liquid and therefore drinkable.
Robber flies don’t sting, and they like to eat things that do (including wasps), but they can pack a mean punch with their mouthparts if mishandled, so it’s not really worth risking picking one up.
This particular robber fly is Milbert’s proctacanthus, or Proctacanthus milberti, and unfortunately that seems to be all that Wikipedia has to say about it.