Stated in MLP wiki:  
Stellar Eclipse is an original character of Sylvain-Nicholas LeVasseur-Portelance. Sylvain has spinal muscular atrophy type III, and through Make-A-Wish Foundation he was able to play as his own original character in the show.
 
Stellar Eclipse is the sixth original character to appear in the show, preceded by Holly Dash, Wild Fire, Midnight Strike, “Slendermane”, and Peachy Pitt.
 
Also look at right, Discord is a lamp, so don’t try to remove the tag, I’ll know it’s gone. ;) XD  
(but seriously don’t remove it)