I mean, Rek'Sai is the largest of her species, so it can't be....
I actually don't know, is Baron from the Void? The lore says he's based off a creature in Runeterra, but League of Legends no longer exists, so Baron is no longer a construct?
Considering Rek'Sai has been on Runeterra long enough to become a Shuriman legend, it is quite possible Baron Nashor is also from the Void despite being described as native to the Rift. It may be that Baron Nashor has been on Runeterra for so long many no longer remember where he truly came from.
Baron is the santa claus of the void Thats why all the voidlings invade runeterra they want to join baron-santa and work for him as his happy-void-elves.
It is quite possible especially depending on if the older rune wars are still canon. It would be nice if the head of lore made a post just saying rune wars are canon, Kalamanda is not canon, Katarina's father being gone is canon and so on and so forth
Every Queen needs a King, right?
May the legendary myth of 
being the real Baron be remembered !
I like to imagine him as being similar to Nidhogg from The Secrets of the Immortal Nicholas Flamel; an impossibly old and ancient entity, from the oldest days of existence, a primal force of nature who is lord and master of whatever dismal part of Runeterra he chooses to grace with his presence.
Do you hear what I hear? A song, a song, high above the trees.
Possibly, but the thing is Baron has no void based abilities at all. It's all acidic and poisonous. That being said Kog'Maw doesn't really have anything to void-y in his abilities, but he's a baby. Baron's a fully grown monster.
The Baron Nasher on the map is a smaller, much less powerful version of the actual Baron Nasher. The first Baron Nasher either died, or went missing, and no one could find it. So the League made a fake version of it, as a construct just like the towers and minions, etc. Baron is not from the void. Baron is supposedly a creature that used to live in Runeterra. I don't know much on the subject, everything I've already typed is all I know.
