Most robust (true) pocket pistol

[brutus51]

I've always had a 1908 Colt pocket hammerless on my bucket list but have never found one I could afford that was in good shape.
Meantime I'm real happy with my Mustang pocketlite.

 

[SDGlock23]

You can make many guns a "pocket" gun if you want, I often pocket carry a G27 or G30, all it takes is a pair of Wrangler cargo pants/shorts. The G42 shoots well, I've had several and I also really like the LCP MAX, quite small with high capacity and usable sights.