18At the end of his first series (Until the Avengers needed him)
The Hulk's first comic book series, The Incredible Hulk, didn't last too long. Debuting in 1962, it saw Bruce Banner struggling to reverse his strange condition. Only a few issues after he was first afflicted with the world's worst temper, Banner invented a device that allowed him to
turn from Banner to the Hulk and back again. Still, each transformation met with more resistance than the last, and in the end Banner decided it just wasn't worth the suffering and the risk to be the Hulk at all. With Rick Jones' help, he used the machine to finally remove the Hulk once and for all, and end The Incredible Hulk at issue #6.
Less than a year later, the Hulk would be needed once more, this time to do battle with Loki in The Avengers #1. No mention was made of Banner supposedly being cured, and the Hulk's popularity was secured.