Constantin Valdor
Constantin Valdor was the original Captain-General of the Legio Custodes. Well known as one of the greatest warriors in the Imperium, to the point where "can he take a Primarch in a fight" is a question taken seriously both in and out of universe. If Malcador was the Emperor's right-hand man, Valdor was his left hand.
History
Unification Wars
Not much is known about Valdor's origins. It is stated that the Emperor spent a lot of time and effort searching for him, suggesting he was somehow special even before his transformation into a Custodes. Although widely believed to be the first of his kind, Valdor himself isn't sure if he was the Emperor's first creation, or merely the first one that actually survived.
One of the first major conflicts that Valdor would take part in was the infamous Battle of Maulland Sen. One of the first major pushes by the budding Imperial forces, it would see the deployment of an entire legion of the newly created Thunder Warriors, alongside the Emperor, Constantin, and thirty of the Custodian Guard.
He would also oversee the eventual death of the Thunder Warriors at battle of Mount Ararat. One last,final stand of Thunder Warriors in defiance against their enemy and certainly not a friendly fire massacre in the name of cold ethics of practicality.
To underscore just how fucking important this guy is - during an attempted Coup d'état he would also command battle ready First Legion Astartes, so there at their birth too. Oh, just as a side he was also there to oversee the creation of their fucking Primarchs and present when they were eventually taken from the facility and scattered.
Guy has been fucking BUSY.
Great Crusade
Not much is known about the shit he would get up to at this point other that he was probably present at the ulanor crusade. Presumably he then made a B-line back to terra with the Emps to help oversee the webway project.
Horus Heresy
Post-Heresy
Eventually Valdor disappeared, leaving behind only his Apollonian Spear. Perhaps he saw how all the Primarchs were doing the "disappear mysteriously so people can spread legends about you returning for the final battle" shtick, and didn't want to be left out.
King in Yellow?
On Tabletop
| Points | WS | BS | S | T | W | I | A | Ld | Sv |
|---|---|---|---|---|---|---|---|---|---|
| 275 | 7 | 5 | 5 | 5 | 5 | 6 | 5 | 10 | 2+/4++ |