Zola is the greatest, and most unsung, villain in the MCU.
Despite Toby Jones only having a handful of minutes of actual screentime, consider this:
*Arnim Zola was already building an army of exoskeletons for the Nazis during the Spanish Civil War in the 1930s.
*Red Skull recruited him and steered him towards biotech and creating an army of HYDRA super-soldiers to combat Erskine's Super-Soldier program for the Americans.
*Zola got hold of one of the most powerful artifacts in the universe and not only figured out how to use it, but converted it to an assembly line that mass-produced the most advanced weaponry mankind had ever seen.
*After the War, Zola was recruited by SHIELD in an "Operation Paperclip"-type spy swap (the same one that saw real-life Werner von Braun start making rockets for America's space program). He used that opportunity to keep HYDRA alive and in the shadows, for over 70 years....right under the nose of Nick Fury himself.
*Zola found a way to transfer his consciousness to a computer, insuring his virtual immortality as an AI.
*Zola created an algorithm that could identify and locate not only *existing* superheroes, but even *potential* ones.....and then kill them all.
*There's a very good chance that Zola could become instrumental in the origins of any combination of Ultron, of (potentially) MODOK, and of "The Clairvoyant" from Marvel's Agents of SHIELD.
Seriously: this dude is badass. He's easily the biggest evil mastermind in the MCU, dwarfing Aldrich Killian, Loki, and even Thanos himself in terms of sheer genius and scheming.