And from a professional standpoint: Haemolytic fevers(Ebola,Marburg,etc.). I am trained to handle patients infected with them.
But boy am I scared by them, especially on a global perspective. And for that reason also fuck everything that lives in Kitum cave or similar caves.
Smart astrophysics people I've talked to are excited when we see gamma bursters further out in the universe than before, because that means that the universe is bigger than previously known.