Cotter and other 'pull' pins
 

First straighten keeper end(s) as much as you can. Fit steel (reasonably hard steel) ice pick or awl into head and gently pry against nut/metal pin is through. Once far enough out to grab with pliers go for it. Get a better grip using wire dams to make indentation with/for pulling.

If this doesn't work tap out from keeper end. :cheers: