Question about brutal strike.
You can only get it as a single classed fighter? So if someone wants to make a gish type (Ftr6, wiz1, abjurant champ PrC), he loses his Brutal Strike?
Or, more likely, say a dwarf takes levels in the Dwarf Paragon class, but is also a fighter. He's emphasizing his dwarfiness (which has fighter as a favored class), at the cost of his brutal strike? Ditto for I think orcs, halforcs, and male drow.

And how does it work if someone is playing a more elegant duelist type fighter?

Why do so many of your fighter feats require odd levels of fighter? Pretty much every core fighter feat requires an even level of fighter. Some based off of BAB only are odd numbers, but those aren't fighter only.
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Unstoppable is pretty much epic level. http://www.d20srd.org/srd/epic/prest...readnought.htm

I like interpose. It might be nice to stick on a devoted defender character (sword and fist)

Unmovable. What do you mean by 'gain half the bonus?' Half the bonus that unmovable grants?

Shrug off Punishment. It looks good, and is close to what a caster gets with a reserve feat. Except casters get infinite uses, and get more abilities than just temp HP. http://dndtools.eu/feats/complete-ma...peshift--1961/ Possibly change it to to be a little stronger or have fewer limits?

Second Wind is nice. But even with a 20 Con, a 10th level fighter is only healing himself by 20 points. Maybe give him uses equal to his fighter level? Personally it reminds me of the healing surge from 4E, and of Iron Heart Surge from ToB.
Delayed CLeave is nice. I might take it if a DM shows up. It's also listed twice.

Fortification. Are you negating the entire hit, or just the fact that it's a critical? Listed twice

Strategist looks like 5 different feats in one.

Penetrate. Don't worry about DR. Most DR is piddling amounts of damage.

Heroic Action. Fighters have little need for swift or immediate actions. ToB characters use them a lot. Even with the other feats you've created. And most people will just take the swift I think. IF they need an immediate, they can just take use their regular swift action for an immediate, and keep their second swift.

You've got a blank after Stalwart.

Great Fortitude already exists. Might want to rename yours. http://dndtools.eu/feats/players-han...rtitude--1263/ Maybe improved fortitude... Grants extra +2 on fort saves (stacks with regular great fortitude)

Imp Great fortitude. Seems odd that it relies on your BAB, and not your con modifier. Maybe include a line that says it should count in place of toughness or improved toughness for prereqs, since it does the same effect.
If renaming your great fortitude, I guess call this superior fortitude

Defensive shield. Could you add a synergy thing? Two people with it, A and B. A fights defensively. B gets the bonuses like you described. B fights defensively, and A gets the bonus.
Can you add a line so that two people using it together get further bonuses? Like the old roman shieldwall?

Improved Defensive FIghting. I think it should require combat expertise, rather than dodge.

Unbalancing blow. Might want to specify that you only make a single melee attack. I can see people trying to combine this with other feats that require a single attack as a standard action. Maybe make it like Power Attack, where it applies on AOOs made during someone elses turn.