The Watchling is a small, mutated enderman with eyes over its head and body, its arms are a bit thicker than its legs, they come in swarms in The End, They are also summoned by The Endersent, which is a Mini-Boss.
Not just the Endersent, They were also summoned by the Eyesent.
They're the from the last Minecraft Dungeons DLC: Echoing Void.