Some of you might be unimpressed by the Metroid protagonist taking the #1 spot, but hear me out because Samus Aran just might be the most dangerous gun-girl on this list. In fact, her abilities not only rival, but surpass Bayonetta's in combat, and here's why.
Unlike Bayonetta, Samus's weaponry has no drawbacks. Should Bayonetta die, her soul is forfeit. While this doesn't matter too much, there is one thing that does: Samus's suit never tries to kill her. In Bayonetta 2, Bayonetta's own demon summoning tries to kill her. Had Jeanne not stepped in the way, Bayonetta would be having a nice date with the devil as her soul gets eaten by demons. Samus? No such problem.
Okay, so maybe that's not fair, but lets look at their weapons. Samus has Power Bombs and the Hyper Beam. Both weapons are capable of penetrating walls, armor, and killing just about everything except for Samus. Even if we take the Hyper Beam out of the equation, Samus's Ice-Plasma-Wave-Long Beam of doom is enough to take out Bayonetta's demons. How do we know this? Because both demons and angels in Bayonetta bleed, and if there's anything that Metroid fans know it's that if it bleeds, Samus can kill it.
If that's not enough of a hard sell for the toughest critics, consider this: Samus has a tendency to not destroy temples or cities. No... Samus destroys planets. Over her career Samus has completely destroyed several planets, namely: Zebes, SR-388, and Phaaze. She also technically destroys Dark Aether if you want to count that too.
Tack on Samus's numerous suit upgrades, energy tanks, and weapons and you have one of the most over-powered heroines in the history of gaming. With such a track record, Samus Aran gets the honor of the #1 spot on this list.