Has anyone ever had their avatar's display name changed without having done it yourself?

[Rolig Loon]

No.

[Rolig Loon]

No.

[Syo Emerald]

No....and I don't even know, if there are rules about displaynames...

[Innula Zenovka]

I've not heard of it.  I suppose LL might change someone's name for them if they received complaints about it being particularly objectionable, but I've not heard of it actually happening.

[Niborrekab Nightfire]

Yes it has just happened to me.  Not sure how it happen though.  Not cool at all

[KarenMichelle Lane]

Here is a question in return.

Was you Display Name change subtlety?

Specifically was a potentially objectionable name change to a slightly different spelling? Or was it simply returned to your default name?

I can imagine LL handling an AR related to a Display Name in this manner of the meaning of the name was objectionable in another language.

[Amethyst Jetaime]

It can happen if your account was compromised and someone has your password either because you gave it to them, you fell for a phishing scheme, or some one easily guessed it. 
I'd change your password if I were you and monitor your account and payment info carefully.  A good password is at least 8 characters long, has both letters and numbers and is a mix of caps and lower case letters.

[Nyll Bergbahn]

I don't use display names so has never happened to me but seems this can inadvertenly occur on the feeds although I can't find anything on inworld changes unless LL take this action at times.

Here is a thread on a display name on the feeds being changed to someone else's username.

http://community.secondlife.com/t5/Everything-Else/Why-is-my-display-name-in-my-profile-feed-replaced-with-someone/qaq-p/1600819

Here is another thread, again to do with the feed.

http://community.secondlife.com/t5/qanda/questionpage/blog-id/sla_everything_else/article-id/6308