Around humans? They act normal around us and our family that they're familiar with, but when strangers (to them) come over, they run and hide.
Around dogs? Well, dogs don't really come over to our house that often, but this one time at our old house, our old neighbors came over and they brought their little Chihuahuas with them and let them run around the house. Let's just say that they did not get along with the cats very well, and the cats started chasing them around the house Tom and Jerry style (I kid you not). Luckily, none of them got hurt.
Around other cats? I can't really say anything on that, because other cats don't really come over to our house.