Osmund Saddler is the main antagonist in Resident Evil 4, and leader of the Los Illuminados. He isn't shown until a good portion of the game has been completed, but his presence is always seen through the horrors he has created in the small Spanish pueblo.
Saddler Is The Final Boss...And Definatly No Cake Walk......When He Mutates You Have Two Options-Which Afterwards Gives Another Two Options-On The Huge Spider Legs There Are Eyes, One Open, Others Closed, Shoot It And Saddler's Head Appears With A Huge Eyeball Either Shoot It Or Go Closer And Slash It With Your Knife Either Will Do Damage. The Other Option Is Limited, Simply Go To Those Platforms With A Switch, Grab The Switch And Wait Until Saddler Arrives Then Use It. This Will Make Him Show The Head Again.
After A Set Amount Of Damage, Ada Will Appear And Hand You A Special Rocket Launcher Either Use It To End The Fight OR Keep Struggling Against Him, It's Possible To Kill Him Without The Rocket Launcher Allowing You To Use Later on Another Boss In A New Game+