Esmeralda was a mentioned character of Trollhunters.
She was a Changeling who worked for the Janus Order. Her base was in Tapachula, Mexico.
Esmeralda was first mentioned in "Grand Theft Otto", when one of the changelings in the Janus Order mistook Claire for her. Apparently, she had killed several humans in Tapachula by opening a dam.
After the destruction of the Janus Order, she is presumed to be dead.
She may have looked quite similar to Claire, since the changeling who saw Claire immediately assumed that she was Esmeralda.