Apple - AutoHotkey Equivalent for OS X?

Check out Hammerspoon. It seems to be very fully featured and — like AutoHotkey — offers a programmatic way to do all sorts of OSX automation, in addition to key binding/remapping.

(It takes a plugin based approach. Karabiner, mentioned in an answer above, can be used as a plugin too allowing its functionality to be enhanced in all sorts of ways.)

http://www.hammerspoon.org/

I recommend Keyboard Maestro which lets you set up macros with various actions that can be triggered with keyboard shortcuts or other triggers.

I use Karabiner. It is a bit of a pain to customize (it uses XML), but it is just as powerful as AHK. It can also move the mouse.