Sifo Dyas

Bit of a cheat here, seeing as Sifo Dyas didn't technically appear in the Clone Wars. It was just an illusion of him after all. But at least we got to see what he looked like.

However, for a character that was so instrumental in how the Clone Wars, and by extension, the Skywalker Saga went, the fact we've never actually seen him is very strange to me honestly. Personally,

I'd like to see him AND his best friend Count Dooku in a show together, set before the Phantom Menace of course, and ending with Sifo Dyas commissioning the army (not his death, as I like the way they revealed it in the Clone Wars).

Barriss Offee

Barriss was Ahsoka's best friend at one point and is a tragic case of how much the horrors of war and the Jedi Code, just don't go together very well. She was an emotionally repressed teenager, not allowed to show grief at her fallen friends. She had a strict master, who basically acted like a nun, and suffocated Barriss' emotions. That would be enough to turn most people to the Dark Side.

She's also the main reason Ahsoka wasn't around to help Anakin in ROTS, and if theories are to be believed, is the one who rescued Grogu from the Jedi Temple during Order 66.

Whether we see her taking care of Grogu after the Great Jedi Purge (and becoming a Light Sider once again), or possibly becoming the First Sister of the Inquisitors, Barriss is too memorable of a character to have no definitive ending IMO.

Duchess Satine Kryze

Living proof that even the biggest rule sticklers (Obi Wan) can be tempted by love, Satine was a very important character in Obi Wan's story. The only woman (in canon) that Obi Wan ever truly loved, as well as an important figure in Mandalorian history.

Obviously, she would have to appear via flashback, which I don't think would be too hard. If Obi Wan gets a season 2 (which I think it will), then maybe Qui Gon can reminisce about Mandalore, and trigger a flashback to he and Obi Wan protecting Satine.

Seeing Obi Wan and Satine in the prime of their relationship, would be a real treat, would give us more Qui Gon and Mandalore, and add further tragedy to Satine's eventual death.

Lux Bonteri

I know he's not everyone's FAVORITE character, but I do think he deserves a proper resolution. He's the one that helped Ahsoka realize the war wasn't as black and white as she thought it was. Ahsoka meanwhile was able to teach him about who he can trust. They grew a lot from one another, and there was romantic tension between the two.

Considering Ahsoka has long since been apart from the Jedi, it would be interesting to see if she and Lux were ever a thing. Or maybe we could see how Separatists endured under Imperial control. Obviously in the Ahsoka show of course.

Revan

I know their scene was deleted but I'm still counting them lmao. Revan was and still is, one of the most famous Star Wars characters to never appear in the movies. Their story, is absolutely legendary, spanning literal centuries, and containing epic stories of triumph and defeat.

Revan is simply destined to appear in live action eventually. If they don't, I think it would be a huge waste. Revan has so much appeal as both a character and a brand, and they should absolutely get their own show. A cameo would never do them justice.

Captain Rex

I know Temuera Morrison has played Clones before, but has he REALLY had a chance to play a Clone properly? He was practically a non-entity in the prequels since the focus was on Anakin's downfall, and as good as his homeless scene in Obi Wan was, it just left me wanting to see more.

Rex is such a great character and helped a lot of fans fall in love with the Clones. Temuera has done great as Jango and Boba, but he really needs that definitive Clone performance in my opinion. This slot could work for Commander Cody as well, but I'd prefer Rex, since he's never appeared in live action before.

Possibly in the Ahsoka show. That would make the most sense to me honestly since he and Ahsoka have so much history together. I just can't imagine Rex making his live action debut anywhere else. If they would rather do Cody, I'd just place him in season 2 of Obi Wan.

The Whills

The Whills are the most powerful beings in the galaxy from what I can tell. They also have a lot of mystery about them. There's so much about them that we don't know. A lot of fans (myself included) are still a little confused about their roles.

They could potentially appear in Obi Wan season 2, giving us a clear reason as to how Qui Gon could become a ghost despite dying before he'd learned how.