What do you call a person who keeps on going despite setbacks? (in one word, a noun)

Solution 1:

Off the top of my head:

• Fighter implies that a person is suffering or has suffered hardships but will persevere.
  
• Trooper is someone who keeps going despite difficulty.
  
• Risk taker implies daring, possibly with a slightly negative connotation.
  
• Determinator is a (highly informal) term for, well, someone who is determined.

Solution 2:

Tenacious.

This does imply resistance, and acting against that resistance.

Solution 3:

If your main criteria is for a word to sound like a person's name, you probably don't want to go for Indefatigability.

Instead, I'd suggest, "Stalwart":

noun
  1. one who has a strong build
  2. one who firmly supports a cause
    "the stalwarts of the Labour Party"

Solution 4:

Perhaps striver. This reference defines strive as

1. to exert oneself vigorously; try hard: He strove to make himself understood.
2. to make strenuous efforts toward any goal: to strive for success.
3. to contend in opposition, battle, or any conflict; compete.
4. to struggle vigorously, as in opposition or resistance: to strive against fate.