Indefatigable: (Adjective) Of a person or their efforts persisting tirelessly.
Scarlett Johansson annoys the piss out of me with her too-cool-for-school nonchalance and holier-than-thou attitude; but I can't say the girl isn't serious about what she does. And you know who else is just as serious and hard-working as ScarJo? That's right: Lindsay Lohan. No really, she said so:
But what hurts me the most is that I work just as hard as any other actress around my age, like Scarlett Johansson, but I just don't get the opportunities that they get because people are so distracted by the mess that I created in my life. But that doesn't mean it's going to last forever." (Source)
Honestly, the only fathomable thing I see in common between Lindsay Lohan and Scarlett Johansson is cup size. And even then I'm pretty sure Scarlett Johansson's anthropomorphized left tit works harder than Lindsay Lohan's.
More of the hardest working girl in showbiz at a nightclub in Miami last week: