Alpha Trion is one of the oldest of all living Transformers in the G1 continuity. Originally going by the name A3, he was one of the first Transformers to rise against their cruel masters, the Quintessons. As a result, he was instrumental in first establishing Cybertron as an independent planet.
On top of this, he is also responsible for creating Optimus Prime and Elita-One!
Alpha first appeared in the season 2 episode The Search for Alpha Trion, wherein he repaired a near-death Elita-One. He would subsequently go on to become the most recurring non-toy Transformer in the animated series.
In the second part of The Key to Vector Sigma, Alpha Trion sacrificed his body in order to to activate the computer long enough to activate the newly created Aerialbots. After this, Alpha Trion's appearances were limited to either time travel stories or stories featuring his ghost.
Interestingly, Alpha Trion is one of the very few Transformers to show signs of aging and hair growth.