Bungie display name, xbox gamertag, and PSN name, can be different, but stays linked. Bungie's display name found in Bungie settings can be changed. Xbox gamertag can be changed but is usually not free to change. Inappropriate xbox gamertag might force change gamertag, check your email or xbox messages to check this. If you think someone got into your account... https://www.bungie.net/en/Help/Article/12718 Edit: looking at your xbox profile's activity feed, "ImNotaReTodd is now known as HappyCalf540172" 6 hours ago, so it looks like a gamertag change from... something. This is not a problem with Bungie, it is a problem with your xbox account, either by inappropriate name or by someone using your account.