A one-armed scientist trying to make limbs grow back, who succeeded on himself and did not stop there.
Curt Connors is the closest thing the Webb films have to a good villain, because his goal is not power. He wants his arm back, and then he wants everyone who has lost something to get it back too, which is where it stops being medicine and starts being a plan for the city.
Rhys Ifans plays the scientist rather than the monster, and the film is at its best in the lab. No Way Home is oddly kind to him: he is one of the characters the plot exists to fix.