Well, John Wayne died onscreen for 8 movies which are:
Central Airport
Reap the Wild Wind
The Fighting Seabees
Wake of the Red Witch
The Sands of Iwo Jima
The Alamo
The Cowboys
The Shootist
Apart from these movies, He was shown dead at the beginning of the movie The Man who shot liberty Valance and the whole movie is his flashback. And In the movie The sea chase, at the end his ship is destroyed by the British and it can be implied that he died as a result.
Central Airport
Reap the Wild Wind
The Fighting Seabees
Wake of the Red Witch
The Sands of Iwo Jima
The Alamo
The Cowboys
The Shootist
Apart from these movies, He was shown dead at the beginning of the movie The Man who shot liberty Valance and the whole movie is his flashback. And In the movie The sea chase, at the end his ship is destroyed by the British and it can be implied that he died as a result.