I think the first time I played Golden Sun the first battle with Saturos took me 2 weeks to finally get through.
Also, this one level in the NES Ninja Gaiden where these GODDAMN MOTHERFUCKING EAGLES keep swooping down and knocking you into pits while you're trying to jump over. Seriously, you know what the biggest threat to humanity is, according to Ninja Gaiden? Not the evil god that's been sealed away, it's EAGLES. I must have died like a billion fucking times to those motherfuckers. The end boss, on the other hand, turned out to be a pushover (By Ninja Gaiden standards, he still killed me like 12 times) once you'd learned all the jumping techniques required to deal with the god damn birds.
Also, this one level in the NES Ninja Gaiden where these GODDAMN MOTHERFUCKING EAGLES keep swooping down and knocking you into pits while you're trying to jump over. Seriously, you know what the biggest threat to humanity is, according to Ninja Gaiden? Not the evil god that's been sealed away, it's EAGLES. I must have died like a billion fucking times to those motherfuckers. The end boss, on the other hand, turned out to be a pushover (By Ninja Gaiden standards, he still killed me like 12 times) once you'd learned all the jumping techniques required to deal with the god damn birds.