Help!

[dovah-kiin]

Okay, so right now I'm creating a character who plays as/pretends to be a rogue, but is actually a spellcaster.

What are the best classes that can help me accomplish this?

[Karnith]

Okay, so right now I'm creating a character who plays as/pretends to be a rogue, but is actually a spellcaster.

What are the best classes that can help me accomplish this?
I would imagine that a Beguiler (from the Player's Handbook II) would serve admirably, assuming that by "pretends to be a rogue" you don't mean "sneak attacks for extra damage all the time."

That, or a cloistered cleric (http://www.d20srd.org/srd/variant/classes/variantCharacterClasses.htm#clericVariantCloistere dCleric) with some good domain choices to get access to skills (e.g. Trickery for Bluff, Disguise, and Hide).

[Callin]

Trickery Domain Cleric toss in the Kobold Domain if ya can swing it

[dovah-kiin]

Yeah, I'm getting beguiler a lot! And no, it's purpose isn't for sneak attacks at all hahaha. It moreso has to do with the plot! My character wants to keep the fact that she's a spellcaster way under the radar.

[Duke of Urrel]

I think both Karnith and Callin have made good suggestions. I also think it's not that hard to pretend that you're not a spellcaster – unless you want to start casting spells secretly while being observed. Casting spells without being noticed requires Sleight of Hand skill, so be sure to invest in that.

You didn't mention what kind of spellcaster you want to be. If it's an arcane spellcaster, a good disguise would be one with heavy armor – preferably illusory armor, of course – because arcane spellcasters are known to avoid heavy armor and the risk of spell failure it imposes. On the other hand, disguising yourself in heavy armor wouldn't make you look much like a rogue, would it?

Which brings me to my second question: Why do you want to pretend to be a rogue? It seems to me that you won't inspire a lot of trust that way...

[Chaosvii7]

I think both Karnith and Callin have made good suggestions. I also think it's not that hard to pretend that you're not a spellcaster – unless you want to start casting spells secretly while being observed. Casting spells without being noticed requires Sleight of Hand skill, so be sure to invest in that.

I've heard plenty of stories of a particular Orc Shaman that pretended to be a Barbarian until about 10th level, when he had to toss a get-out-of-jail-free card to his party. Made all the checks and everything. I have no problem believing that it's possible to do, even with a regular full spellcaster. It's all about appearances.

That said, Beguilers are specifically spellcasters that fulfill the rogue archetype. An alternative would be the spellthief, who actually steals spells, but the power of the class is debatable and is usually no better than Tier 3 with proper optimization.

[gorfnab]

There is also Psychic Rogue, Lurk, Factotum, Trapfinding Mystic Ranger, Nightstalker, and possibly Bard.