Starting off with Captain America, horror and romance comics, after a brief try out on Daredevil, John was quickly moved to the Amazing Spider-Man where he made his mark on the world.
So successful on Spider-Man, John became Marvel's art director, shaping Marvel Comics for decades to come (and, after his incredibly powerful cover to Marvel Treasury Edition #1 of September, 1974, he did a few other Treasury covers, include as well, to show how epic his work could be).
Marvel Treasury #2 and #3 1974
Marvel Treasury #5 and #8 1975
...was the humanity he brought to his art, evidenced by this shot from the 1978 Spider-Man calendar (April), of Peter Parker and his cast outside the Coffee Bean.
here, and even some DC work here!