The old Microsoft Encarta encyclopedia had different
    facts for different countries. In the US edition, Thomas
    Edison invented the light bulb, while the British version
    said it was Sir Joseph Swan.

If you search for "lightbulb inventor" on Google [1] it currently shows three "lightbulb inventors": Thomas Edison, Hiram Maxim, and Joseph Swan.

[1] https://www.google.com/search?q=lightbulb%20inventor