I believe it was introduced by Prophecy. It was the light torpedo... I'm not sure how it's related to WC3's variant, though. As far as i know it was only known as "torpedo".
Prophecy had Lancer Light Torpedoes and Pike Torpedoes... but I'm referring to knowing the class before Prophecy ever came out. If not the regular version, maybe the 3DO or PSX weapon selection screens?