Loch Ness = No.
Flying Saucers = No.
Ghosts = Absolutely.
Sasquatch = No.
Aliens = Yes, but not the ones "spotted" in tabloids.
Giant Squid = Yes, they've been proven to exist.
Jaws = Yes, white sharks have been known to exceed 30 feet in length.
Super Anaconda = Yes. I'm sure some Anaconda's can grow quite big, with all the snake-worshipping natives to feed on.
Basically, I believe in ghosts and I believe there is other life outside of our solar system... but that's about it.