If Galactus is set to become the Next Major Antagonist in the MCU who will become Secondary Villain?

Probably one of his heralds. That would only make sense. Or maybe Kang.

People like Doom and Magneto are big enough to be main villains as well.

Annihilus and The Annihilation Wave for the win.

Most likely Dr. Doom.

His herald or Annihilus

Doom first and then one of his heralds leading up to Galan

Should be Doom

I feel this is likely since they have established there is a multiverse..

Kang Because of Time Travel Questions...Descendant of Stark Lots of Room to Work with He can Easily Explain X-men with Kang other Timelines go in depth with the Anti-Back to the Future Logic

Kang

Kang

Has to be Doom. Move from Doom to Galactus as they did from Loki to Thanos. Throw Silver Surfur and heralds for the Phase 5 Avengers.

Toad.

Doom

From the list Kang. But i prefer other choices.

It needs to be fresh, otherwise may as well bring back the Surfer.

If its Galactus Doom will probably end up being the main villain