Bluetooth was named after Harald 'Bluetooth' Gormsson, a 10th century Scandinavian King who united Denmark & Norway, and it's logo is a rune of his initials. 

Initially, 'Bluetooth' was a placeholder, and was either going to be called either RadioWire or PAN.

Bluetooth was named after Harald 'Bluetooth' Gormsson, a 10th century Scandinavian King who united Denmark & Norway, and it's logo is a rune of his initials. 

Initially, 'Bluetooth' was a placeholder, and was either going to be called either RadioWire or PAN.

https://www.bluetooth.com/about-us/bluetooth-origin/