I've done a few of these Hair Timelines now, and for no particular reason I think this week would be a good time to cover the hair (and lack of) of Asajj Ventress!
Before 23 BBY: Short Dark Hair
In flashbacks of her as a young padawan, we see Ventress with short, partially shaved dark hair. It's a look I think suits her really well, and I hope we get to see some more of padawan Ventress sometime, or maybe even early dark apprentice Ventress still rocking this look.
22 BBY: Bald
Ventress' most iconic appearances in The Clone Wars all have her completely bald, meaning we get to see some of those really cool tattoos on the back of her head, and also that characters like Ahsoka get to throw around insults like "hairless harpy."
19 BBY: Short Blonde Hair
Starting in the Dark Disciple novel (and can be seen in the character sheets and unfinished reels from the unreleased episodes of The Clone Wars the novel is based on), Ventress begins to sport short blonde hair, similar in style to her old dark haircut (though perhaps a little bit longer). She continues to wear her hair like this post-resurrection in The Bad Batch, and we'll see how long the look sticks around for her in the future!