Lilith from Borderlands 2 is the Firehawk!
Give Lilith the Siren from the original Borderlands some Eridium and she will start using her phasewalk powers and toss enemies around like there is no tomorrow!
This fan art by Sentrythe2310 made me wanting to get Lilith as another additional and playable character for Borderlands 2 even more. Using her strong Siren Abilities but also being in need of the Eridium Element could be a nice new gameplay mechanic which adds a whole new element to Borderlands.