I know that nobody is going to beat Jesus in this category, but are there any historical or literary or Lady of the Lowlands types that have had several songs written about them? There are plenty of "Mary"s (Springsteen alone must have five or ten) but I’m talking about subjects that are a little more specific.
If her autobiography is to be believed, Patty Boyd inspired George Harrison’s “Something” and Eric Clapton’s “Layla”, “Wonderful Tonight,” and “Bell Bottom Blues.”
Romeo pops up in a lot of popular songs, with and without Juliet. Sometimes the name refers to a specific literary character and sometimes it’s a signifier for any young man or boy in love, so I’m not sure how you’d count all the references. R&J have also inspired dozens of operas, symphonies, etc.
HW also features strongly in Beck’s Loser “I’m a driver, I’m a winner, things are going to change, I can feel it.” and KMFDM’s A Drug Against War. “Bomb the living bejeebus”