This is a species of biting horse fly.
Its body lenght is 16–22 mm.
Horse flies are big, fast-flying creatures, and they will bite any big mammal, including humans.
The bite is very painful, as they cut the skin when they bite (rather than pierce it).
Horse fly bites can take a long time to heal, and can cause infection.

A male. In my yard, Hilversum, The Netherlands, 15 June 2014