Technically 3… 
See? this post at the time was hidden by a moderator as it was considered an exploit… but there I explain how this happens in detail. (TLDR they’re reusing templates designed for humans because the other stats would match nicely, but they overlook the XP amount)
I guess I can link it now that it was patched a long time ago
So there were those golems with their casual 190 million XP… there is still the dragon that they forgot about… but that one is a “hit or miss” because when things go right it doesn’t award XP to the player since it auto-dies…
If by some mistake the timings go wrong and the player remains the “killer” when it dies, then it may accidentally award their very high xp, but it typically only happens on laggy servers.
And now this one with the commander was the third…