Plastic Man!
 
This is the cover of the January 1943 issue of Police Comics where Plastic Man made his first appearances before getting his own magazine in the late 40s.

He stretches! He bends! He's Plastic Man!!

"Four-color Plasticman goes oozing out of a keyhole, around a corner and up through piping that leads to a sink in the mad Nazi scientist's lab, out of whose faucet Plas' head now, blank carapaced eyes and unplastic jaw, is just emerging. 'Yeah. Who're you, Ace?'"
(p.206)

"--a mad Nazi scientist lab! Plasticman, where are you?"
(p.314)

"varoom, a Plasticman sound"
(p.331)

"Plasticman will lose his way among the Imipolex chains, and topologists all over the Zone will run out and stop payments on his honorarium checks"
(p.752)