Sabine Wren in Trials of the Darksaber (this is one of my favorite pictures of this beautiful Mandalorian, and the episode is amongst the best of Star Wars Rebels)
Shout out to Dave Filoni and the cast and crew of Lucasfilm Animation for creating yet another great show over the past four years.
Below is a PDF I created showing the changes Sabine made to her armor and hair throughout the four seasons of Star Wars Rebels.