I killed a dark flying insect that landed on my leg which smeared a large amount of black blood across my leg and hand what kind of insect could this have been?

Answer 1

There are many insects that feed off the blood of its host, most common of these are mosquitoes, fleas and ticks. Of those, the only one that flies is a mosquito, and it was either filled with your blood that it just fed on, or another person or animal.