Monster Hunter Vendetta

Owen Zastava Pitt, accountant turned professional monster hunter, managed to stop the nefarious Old One's invasion plans last year, but as a result made an enemy out of one of the most powerful beings in the universe. Now an evil death cult known as the Church of the Temporary Mortal Condition wants to capture Owen in order to gain the favor of the great Old Ones.

The Condition is led by a fanatical necromancer known as the Shadow Man. The government wants to capture the Shadow Man and has assigned the enigmatic Agent Franks to be Owen's full-time bodyguard, which is a polite way of saying that Owen is monster bait.

With supernatural assassins targeting his family, a spy in their midst, and horrific beasties lurking around every corner, Owen and the staff of Monster Hunter International don't need to go hunting, because this time the monsters are hunting them. Fortunately, this bait is armed and very dangerous.

The Monster Hunter International series by Larry Correia:

Monster Hunter International
Monster Hunter Vendetta
Monster Hunter Alpha
Monster Hunter Legion
Monster Hunter Nemesis
Monster Hunter Siege
Monster Hunter Guardian (with Sarah A. Hoyt)
Monster Hunter Bloodlines

The Monster Hunter Memoirs series:

Monster Hunter Memoirs: Grunge (with John Ringo)
Monster Hunter Memoirs: Sinner (with John Ringo)
Monster Hunter Memoirs: Saints (with John Ringo)
Monster Hunter Memoirs: Fever (with Jason Cordova)