Alternative Foreign Theme Song
When a dubbing company wants to market a television show, film, or video game from another country, they'll do the usual stuff like translation and localization. But they've got one problem with it: they don't think its theme song will be suitable to the tastes of foreign viewers. So what do they do about this? Instead of dubbing the original song, they'll replace it with a completely different theme song, of course! Maybe they believe the new song will make the show more popular with their foreign audience, or maybe the original theme song is licensed by a singer and they can't use the music. The tune of the new theme song will most likely bring out a very different mood. This can qualify for both the opening and ending theme. This is common for English dubs of anime series geared towards children, especially if the show is airing on a television network, but it happens outside of North America as well; the practice of having completely different music is arguably even more common in Japan, where there is an entire industry based around creating Anime Theme Songs, and Italy, where it's easier to list the animated series who don't have at least one. This is also an aversion of The Song Remains the Same, where the original song is kept and left in its initial language, and Translated Cover Version, where the original theme song is dubbed with more-or-less a direct translation of the original lyrics. If the song keeps the same melody of the original, but has radically different lyrics, then it goes under What Song Was This Again? Not to be confused with Foreign Language Theme, where the original theme is written in another language, or Replaced the Theme Tune, where the show replaces its own theme song with another one.