Where to download Flash Player for offline installation?
Edit 2017: The installers are now at http://www.adobe.com/products/flashplayer/distribution5.html
It seems that the link below does no longer give access to offline installers :(
Download Adobe Flash Player 16 / 13 / 11.2 full offline standalone installers (MSI/EXE) for Internet Explorer / other browsers:
I've contacted Adobe because I was completely unable to install Flash with the 900kb installer-downloaders which always flood me with strange errors (and delete themselves from the run location! so you can't launch the installer-downloader after failure, have to re-download it), and they sent me this link.
For a long time, I've been taking the offline installers from this page: Installation problems for Windows 7 and older (already mentioned in a comment by Fronker).
The links are always up-to-date, and it lets me get all plugin architectures (as of today ActiveX, NPAPI and PPAPI). The links are near the bottom, under the Still having problems? heading.
The above instructions are for Windows, but the same approach works for Mac OS X. Here's the Adobe help page with the offline installer links at the bottom: Installation Problems – Mac. This Adobe help forum page is also helpful: How to perform a "clean install" of Flash Player in Mac OS X.
Adobe has decommissioned the Distribution page, but here's another method that still works for now:
On the standard installation page https://get.adobe.com/flashplayer/ the "Install Now" button links to the download page
https://get.adobe.com/flashplayer/download/?installer=..., you should append
&standalone=1 to the end, then it'll let you download the normal standalone offline installer.
P.S. Don't forget to disable "Optional offer" before copying the link.