Who is/was Poin-Dexter?

Poindexter was the boy in the cartoon Felix the Cat. He was the nephew of Felix's arch nemesis the Professor. I think Poindexter was also a character on the "Rocky The Flying Squirrel Show" where he played opposite a smart dog. I don't remember the dog's name. It was probably a parody of the Felix the Cat stuff. Sorry, that was Peabody and his boy, Sherman. But the Felix the cat stuff is right.

John Marlan Poindexter (born August 12, 1936 in Odon, Indiana) is a retired American naval officer and Department of Defence official. He was Deputy National Security Advisor and National Security Advisor for the Reagan administration. He was convicted of multiple felonies as a result of his actions in the Iran-Contra scandal. His convictions were eventually reversed on a legal technicality.

Homer keeps on calling Milhouse pointdexter on "The Simpson".

That episode is probably 5 years ago.

poindexter was a nerdy scientist type in "Felix the Cat"

he was also the name of a brainiac-type in "Archie Comics".

How "poindexter" became associated with nerdy types is anyone's guess

A stern hypocrite.