"And In This Corner... Goliath!"
by Roy Thomas, Gene Colan and George Klein
I knew of this Goliath long before I ever knew Henry Pym had been the giant hero. I also didn't figure out Hawkeye was this Goliath either for a while. Of course, I never read this origin story until it was reprinted in Marvel Super Action, but I love this costume. The vagaries of reading stories out of order when I was a kid.
Roy effectively sets the stage for Hank's later nonsense with schizophrenia, but I doubt he had this in mind when he wrote this story. Hawkeye wants to be the powerhouse of the group, and does so for the next 35 or so issues. It all works well and we even get to see the Black Widow as well.