Cap vs. Gipper-zilla from marvel.wikia.com
We next turn our attention back to Marvel and Captain America, issue #344, to be exact. At least at DC Comics' chief competitor President Reagan got a fair shake, in that his supervillainy was not of his own will and was eventually reversible.
In this August 1988 comic the supervillain Viper and her evil Serpent Society pollute the drinking water of Washington DC with a mutagen that will turn humans into mutant snake-people. Their plan is to bring America to its knees by transforming its leaders into a city full of ravening reptillian monsters.
While Captain America inevitably stops the villains and cures the city, he must win a fist-fight with a rampaging, mutated Serpent-Reagan. While the President in the story was merely acting under the temporary influence of a gene-splicing toxin, it can't have pleased the White House to have our Commander in Chief labelled "THE DEADLIEST SNAKE OF ALL!"