Swashbuckler with better-than-rogue Sneak Attack (3.5e Optimized Character Build)
From D&D Wiki
This is a Swashbuckler build with better than Rogue Sneak Attack and full BAB, and the ability to feint every attack. Until level 9 you operate as a Swashbuckler who two weapon fights. At level 9, you turn into a sneak attack monster.
Player's Handbook, Complete Warrior, Complete Scoundrel, and Unearthed Arcana with flaws rule variant are all that's needed. Races of Destiny and Spell Compendium are optional.
 Game Rule Components
The best magical Kukri you can get and multiple Daggers for throwing at full BAB.
Starting Ability Scores (Before Racial Adjustments):
Maximize STR and INT for maximum damage output, maximize CHA for bluff.
On 32 point buy:
16 STR 12 DEX 10 CON 16 INT 10 WIS 14 CHA However you need 17 DEX to get Improved Two-Weapon Fighting
All stat raises should go into Str.
Requires Human for maximum potential.
Starting Racial Traits:
|Saving Throws||Feats|| Class
|1st||Swashbuckler||+1||+2||+0||+0||Point Blank Shot, Far Shot, Two Weapon Fighting,||Weapon Finesse||Boring|
|3rd||Swashbuckler||+3||+4||+1||+1||Weapon Focus Kukri||Insightful Strike||Boring|
|5th||Swashbuckler||+5||+5||+2||+2||--||Dodge Bonus +1 ->||Boring|
|6th||Invisible Blade||+6/1||+5||+4||+3||Improved Two Weapon Fighting||Sneak Attack +1d6, Unfetteredd Defense||Boring|
|7th||Invisible Blade||+7/2||+5||+4||+3||--||Bleeding Wound||Boring|
|8th||Invisible Blade||+8/3||+6||+4||+3||--||Sneak Attack +2d6 Uncanny Feint(Move Action)||Boring|
|9th||Invisible Blade||+9/4||+6||+5||+3||Daring Outlaw||Feint Mastery, Sneak Attack +5d6||Holy crap, you did 1d4+str+int+5d6 4 times against a flat-footed creature!?|
|10th||Invisible Blade||+10/5||+6||+5||+3||--||Sneak Attack +6d6, Uncanny Feint (Free Action)||Holy crap, you did 1d4+str+int+6d6 4 times against a creature that wasn't flat-footed!?|
Final Class Progression: 5 Swashbuckler/5 Invisible Blade
 Other Components
For flaws, if your DM only allows what is in Unearthed Arcana, I advise Shaky, Frail, or Vulnerable, or as many as he'll let you take. Otherwise, there's a few nice ones around D&D wiki. If he won't let you use flaws, find a different build.
Note: Able Learner is optional if you can take 2 flaws, if you can only take 1, take Two Weapon Fighting.
Daring Outlaw makes Rogue and Swashbuckler levels stack for Sneak Attack, the prerequisites for the rogue side is +2d6 Sneak Attack. Since Invisible Blade doesn't require Sneak Attack to qualify for, it makes it a prime choice for this feat, as well as feint mastery. EDIT: The only problem being, Invisible Blade is not Rogue.
Invisible Blade level 5 makes feint a free action, you have infinite free actions in a turn, so you can feint all of your attacks. EDIT: the latest errata of Complete Warrior nerfed this feature: you can only feint once as a free action in a round.
At level 15 you can have 9 attacks at +8d6 Sneak Attack, via Kukri of Speed.
Oh, and don't forget, you're always aiming for flat footed.
 Munchkin-Size Me
As for progression beyond 10, my advise is 5 levels of Swashbuckler then 4 levels of Rogue for evasion and uncanny dodge, then a level of Swashbuckler then Rogue for epic levels, to get the random class features like improved evasion and improved uncanny dodge. Also the extra skill points rogue get are great combined with Able Learner, you can dump a few into a lot of random skills.
[Edit] after level ten I suggest taking at least a one level dip into barbarian with the lion totem variant out of the complete champion (not the UA lion totem), this will give you the pounce ability. Now you can make a full attack on a charge. Then back to swashbuckler for acrobatic charge, so by level 13 you can charge basically any were and make a full attack with sneak attack and all your other bonuses.
Beyond level 10, get Kukri of speed a Cloak of Charisma +6, Belt of Strength +6, Headband of Intellect +6, Boots of Speed, and wands(Dump Skill points into UMD.) of Golem Strike(Sneak Attack v Constructs, Spell Compendium) and Grave Strike(Sneak Attack v Undead, Spell Compendium), Wand of Greater Invisibility is nice. Also, anything that increases charisma/bluff is great, traits, items, feats (possibly). Oh, and don't forget to take greater two weapon fighting at level 12.
Leadership with a cohort of an Artificer or a Wizard with feats dedicated to crafting is greatly suggested.
With boots of Haste you can take a standard to close distance then make a full attack. Optionally, you can use it to activate a wand of Grave Strike or Golem Strike, which is best combined with greater invisibility due to attacks of opportunity.
Not even death will escape your Kukri.
 Side Notes
High bluff is required for this class to work, you can take 10 on all your feints, and I advise doing so unless you're against an enemy with a high sense motive, in which case, try to get Greater Invisibility. A fighter with ranks in sense motives will probably pass his check every time if you don't specialize.
Undead and Constructs will take regular damage without the wands mentioned in Munchkin-size me, also, feint is versus Sense Motive+Base Attack Bonus, very few monsters have it, but DMPC's might, and this can cause a problem.
 DM Counters
Throw out a lot of undead or constructs, have heavily armored enemies, since their flat-footed AC tends to be higher..
Also note, feint save is sense motive+Base Attack Bonus, so send enemies with either a high BAB or a bit of both.
Daring Outlaw feat stacks rogue levels with swashbuckler levels, not any class with a sneak attack progression. You can also argue that Invisible Blade says "Dagger Sneak Attack" and therefore doesn't qualify for Daring Outlaw.
 Closing Notes
As someone who loves highly martial characters, this build can still operate for support, since it has UMD, you'll just need to replace skill with magic. Need to pick a lock? Wand of knock.