OK I'm looking for a pistol powder that will work with 9mm, 38 special, 357 sig, 40 and 45 acp and if it will work with a 12 gauge shotgun even better. If i had to pick the two most important calibers it would be the 9mm and 45 acp.
I know one powder is not going to be the best for all these but I'm talking one power to have on hand that will "work safely" with all these. Thanks

Green dot or Unique would get my vote for alliant powders. How about universal for hodgdon or #5 for accurate powders. I'm not sure of the metering in the last two mentioned. Something in the Vihtavuori powders should work also.

I use Titegroup for 9, 38, 40, 44spl, 45acp, and 45LC.

Titegroup.
Also if you like a softer shooting powder Clays works great but I've only used it in 9, 40 &45 acp for shooting idpa

Unique is the Swiss Army knife of powders. You can load dang near anything with it, but it does tend to be a little bit more difficult to meter.

Another vote for unique, while it is not great in anything it's dang good in just about everything

Hogden Universal Clays works well in all mine

I use WSF in a few pistol calibers and 12ga but I'm not sure it would do all of those on your list.

Universal Clays works well in 12-gauge, and I see no reason it won't work fine in the handgun cartridges mentioned.

Titegroup is good, as well as Unique. But these powders are not that great for 357 Sig or shotgun, and it depends on what bullet weights you plan to run in each caliber. I know it makes it easy to just pick one powder and load it for all. But you sacrifice so much potential from the cases that aren't ideal for that powder. I like having several powders to use, so when you can not find your one "go to" powder, you are not SOL. And you can optimize the round for the bullet you are shooting.

I'm that way. I'll buy powder for one round and end up using something else so I have a few pounds that haven't even been opened yet, but I always will have a back up just in case. Most of the stuff is generalized into burn rate so it can interchange with the same bullet weight.

This is a question a novice to reloading would ask. Powder is the least expensive component in reloading. Experimentation with different powders all a part of the reloading/shooting experience and just as much fun.

Unique to answer the question of the OP.

Thanks everyone. One that no has said yet is Red Dot? I used it many years ago when I was reloading 12 ga. I see it shows up a lot in my reloading books (most ten years old or older) for all calibers I was asking about. Is there a reason to stay away from Red Dot (Dirty maybe). Again I realize no one powder is going to work great in everything. I am more or less looking for something to have as a back up that will work OK in a lot of different situations when no other powder can be found. thanks again