…Can you? Is it supposed to be anonymous or do they already know who you are from reading the rest of your application?
Does it make a difference in scholarship essays vs. the common app and similar essays?
Thanks! 
You can use your own name- it is certainly not an anonymous essay & the goal is for the AO to come away thinking, “SuperSenior19 is just the kind of student we want”.
However…writing about yourself in the 3rd person is a tricky business, so whether you should or not is down to how well you can pull it off.
Why can you use personal pronouns, “I” or “me?” It’s awkward to refer to yourself otherwise, questionable. The college app isn’t the place to test readers. The exception is a direct quote.
I was thinking more along the lines of a quote from another person, or narrating my own thoughts to myself (eg, “Focus, SuperSenior19!”). I was going to keep it short, if I include it at all, but I can definitely see how it would be awkward or make for a clunky transition. Thanks for the advice!
I think my S had a line that involved others addressing him “Hey, MathKid,…”
I didn’t think that was awkward, and yours example doesn’t sound awkward either. At least not necessarily.
Be careful with this idea, Bob Dole.
(OP, you’re probably too young to understand the reference… google “Bob Dole third person”)
Your example is a direct quote. Fine.
If your essay says …
“I heard my sister Malia saying ‘Sasha, I can’t believe you got the best room in the house!’ when she came back from Harvard…”
then I think it will probably help if your essay includes your first name.
Again, it’s a direct quote. You wouln’t want to write, “Sasha got the best room,” if you’re Sasha. Or Sasha visited her sister."