The legendary ancient Transformers who were the first created by Primus, not all of them have been revealed.
To combat the chaos bringer Unicron, Primus created thirteen powerful robots, these 13 original transformers fought against and defeated Unicron, but soon after began to turn on one another. All transformers are their descendents.
Prima: The first to be created, Optimus Prime is a direct descendent of him
Alpha Trion: The emissary of Primus, exists multi-dimensionally, aware of all realities
Vector Prime: The guardian of the time-space continuum
Megatronus Prime/The Fallen: The first to betray his brothers and sister(s?), Megatron is descended from him
The Nameless Ultimate Evil Counterforce of Good/Liege Maximo: The first who Primus likely intended to be evil, the Decepticons are descended from Liege. He has no name and is simply known by his rank
Solus Prime: First female Cybertronian, she is a skilled weapon maker, creator of the Star Saber, Requiem Blaster and more.
Amalgamus Prime: First to have the shape shifting ability, he was not limited to a single alt-mode and could become anything he desired to be.
Nexus Prime: The first combiner, all his sub-parts are simply counted as a single representative of the first 13
*Minicon Prime: The first Minicon, he and his descendents remained neutral.
*Beast Prime: The first beast mode transformer, the Dinobots, Maximals and Predacons are likely his descendents
(*fanon names, no official name has been provided)