Omniglots

Omniglots are those that speak in multiple languages, three or more, fluently. Most people find it hard work to achieve native-level fluency in just one foreign language, even when they're a full-time student of it, but characters in stories might speak thirty languages well enough to be mistaken for a native speaker in each. Sometimes there may be justification for this — perhaps it's a superpower, perhaps the character is immortal (and thus had the time to learn the languages the regular way) or perhaps they had an Upgrade Artifact.