Darth Tenebrous's lightsaber
A lightsaber with a crimson blade was created by Darth Tenebrous, the Dark Lord of the Sith who was a Bith, while he was an apprentice being trained by his master. The blade was red.
History
During his time as a Sith apprentice, Darth Tenebrous made a red lightsaber for himself. He would then use this weapon to practice his lightsaber combat techniques and during sparring matches.