Well, I remember that boss in Ocarina of Time's Water Temple being a total pushover. I think we can agree that a boss you can take without losing a heart on the first attempt without having read anything about it on the net is an easy boss.
Of course, it's sort of hard to define "easiest", because these days, so many games have a first part or first level that is sort of tutorial-ish, so naturally, you won't be in much danger there.
The first area and boss in Suikoden V is laughable, though. Because it's not just easy, it's pretty much impossible to get a Game Over screen. Really. Just stroll through the woods, using Auto in all battles, including the one against those three wolves. At worst, you -might- have one or two characters knocked out (if you're unlucky), but Georg makes it impossible to get a Game Over screen. Heck, even if you simply put him on Defend all the time, he'd probably end up countering the enemies to death before his own HP was whittled down.
And the next few areas are also like that. You really need to -work- to even be remotely in danger in most of the early parts of Suikoden V. Which is sort of the opposite of how it should be, isn't it?