To whom was Yoda referring when he said, "There is another?"

Question

In the original trilogy Yoda refers to another hope:

Obi-Wan: "That boy is our last hope."
Yoda: "No...there is another..."

The assumption being after seeing Return of the Jedi (Episode VI) that the other was Leia.

If, however, you consider the prequel trilogy canon, then this assumption depends greatly on your point of view*. Obi Wan knows about Leia (and for unknown reasons has discounted her as a hope), so Yoda must be referring to someone or something else.

Is there any canonical source as to what Yoda meant, or was uncle George setting us up for Episode VII?

*as a wise man once said

you will find that many of the truths we cling to depend greatly on our own point of view.

Just to add a bit of clarity: I was thinking about who Yoda was referring to when he was talking to Obi-Wan. When talking to Luke, it is obvious that Leia is the other (as he talks about a 'Skywalker'). It is not so obvious (after watching the prequel trilogy) that he means it when talking to Obi-Wan.

Answer 1

This dialogue from Star Wars episode VI Return of the Jedi made it clear it's Leia :

BEN: Then the Emperor has already won. You were our only hope.

LUKE: Yoda spoke of another.

BEN: The other he spoke of is your twin sister.

LUKE: But I have no sister.

BEN: Hmm. To protect you both from the Emperor, you were hidden from your father when you were born. The Emperor knew, as I did, if Anakin were to have any offspring, they would be a threat to him. That is the reason why your sister remains safely anonymous.

LUKE: Leia! Leia's my sister.

Answer 2

As a further confirmation to DavRob, Episode 3 (at least Matthew Stover's novelization that was approved and edited by Lucas, not sure about the script of the movie) confirms that Yoda ALWAYS meant Leia by "another" hope:

"... Hidden, safe, the children must be kept. Foundation of the new Jedi Order, **they will be**."
"We should split them up," Obi-Wan said. "Even if the Sith find one, the other may survive. I can take the boy, Master Yoda, and you take the girl. We can hide them away, keep them safe— train them as Anakin should have been trained —"
... When right is the time for skills to be taught, to us the living Force will bring them. Until then, wait we will, and watch, and learn."

Answer 3

If we are to assume that Yoda's statement that 'there is another hope' has any thematic relevance to the movie in which is takes place, Yoda must be referring to Vader, since Leia does not save the Galaxy. The entire Star Wars saga is about Anakin's redemption, and how his redemption is the only way in which the darkside can be defeated. Thematically, it makes no sense for Yoda to be referring to Leia, other than to state that the Jedi have no idea what they are talking about, which they certainly do not if they are referring to Leia.

Answer 4

The original pre-SE/pre-Prequel novelization of Return of the Jedi explains very clearly that Leia was meant to be trained as another Jedi.

Ben and Luke are discussing whether or not Leia might be able to help sway Vader.

"She hasn't been trained in the ways of the Jedi the way you have, Luke - but the Force is strong with her, as it is with all of your family. That is why your path crossed mine - because the Force in her must be nourished by a Jedi. You're the last Jedi now, Luke... but she returned to us - to me - to learn, and grow. Because it was her destiny to learn and grow; and mine to teach."

Answer 5

I'm going to necro my own question here as I've finally found something semi conclusive.

Let's work backwards on the known continuity

Here in 2024 we know that Obi Wan knows Leia and the "that boy is our only hope" line is down to bad continuity

The "other" question was answered really in 1983 with the release of Return of the Jedi. Most answers to this question refer to this.

But from 1980 to 1983 the questions was open. It's also worth remembering that Lucas cut back a lot of plot lines to be done with Star Wars after Jedi. (The world couldn't wait longer of Howard the duck obviously)

It's pretty clear that if at the time of writing Luke and Leia were planned to be siblings that Empire would be a little less incestuous. So there was an original plan for something else to be the other hope.

Since this question was asked the first draft of the episode five script has appeared it resolved this a little.

There is a good write up on slash film

From the article

Luke leaves his Jedi training with Yoda to go rescue his friends from Darth Vader. Yoda regrets this, as Luke is not yet ready to be a Jedi Knight. Yoda holds out hope, however, saying "There is another." Brackett's script also had that line, but it was more explicit as to who the "another" was. It seems Luke still had a long-lost sister named Nellith. 

From the script (on Degoba and Skywalker is a force ghost)

SKYWALKER

You’ve grown well, Luke. I’m proud of you.

(Luke, not knowing what to say, says nothing)

Proud, and afraid for you. You’re going into battle untried. Did your uncle ever speak to you about Nellith?

LUKE

Nellith? No. Who is she?

SKYWALKER

Your sister.

LUKE

My sister? I have a sister? But why didn’t Uncle Owen….

SKYWALKER

It was my request. When I saw the Empire closing in, I sent you both away for your own safety, far apart from each other.

LUKE

Where is she?

SKYWALKER

If I were to tell you, Darth Vader could get that information from your mind and use her as a hostage. Not yet, Luke. When it’s time…"

Answer 6

As it says in the novel of ROTJ... Luke said "But you can't let the Emperor of Vader get their hands on her (Leia). Obi-wan said "She hasn't been trained in the ways of the force as you have Luke. You are strong and patient now, and you're ready for your final confrontation"

Luke was the only hope because if he failed, there was now NO one left to train Leia in the ways of the force. Yes, she would have the same potential, but it would be wasted because now that both Obi-Wan and Yoda were physically gone, there was no way that Leia could be trained as a Jedi.

Answer 7

I'm going to go against mainstream opinion . It is definitely NOT Leia . It could only be redeemed Anakin Skywalker. There are several reasons for this:

1. Like it or not, Leia is only supporting character in whole saga . Ok, she had Death Star plans in Episode 4, but after that her significance is much reduced. Yes, she is Force sensitive, but as far as we know, never near potential of her brother or father . And who would have trained her, even if she somehow escape from Endor ? Force ghosts ? From all that we know Jedi training requires grueling regime for months and years. Luke trained long and heard on Degobah, but despite all of that was no match for Palpatine . And as far we know, Force ghosts could appear only for short time (few minutes, or even seconds) . Otherwise, Yoda and Kenobi could train not one, but many Padawans across whole Galaxy, because there are still many Force sensitive children/younglings .

2. Significance of sentence There is another Skywalker is much increased in Clone Wars last episode "Sacrifice" . If you consider another Skywalker to be Leia, significance of this phrase would be practically non-existent. Both Luke and Obi-Wan Kenobi knew that Leia exists and that she has some Force talents . In the end, she doesn't do anything extraordinary, so why would Force Priestess utter this phrase to bewildered Yoda as her (and years latter his) final words ? There must be something else .

3. Both Yoda and Kenobi considered Anakin Skywalker to be as good as dead . "More machine then a man", "Darth Vader betrayed and murdered your father" and especially Once you start down the dark path, forever will it dominate your destiny, consume you it will. Yoda thought and taught Luke that there is no coming back from Darth Side. This is old and dogmatic view of Jedi Order before Order 66. Force Priestess in last episodes of Clone Wars tried to teach him something else. Yoda understood that there is some Dark Side in everybody, even him. But yet he still thought he has nothing to learn from Sith (encounter with vision of Darth Bane and illusion of Sifo-Dyas) . In other words, he could not sense good in them - right until his dying moments. Only then he realized that simple truth - Anakin Skywalker is still alive. Suppressed, wounded, half-mad but still father of the boy standing before him. And yes, redemption is possible - there is another Skywalker, one destined to destroy Sith and bring balance to the Force. Which he did .

Answer 8

There is a speculation that "another" could be not a Skywalker at all, but Ahsoka. She was already trained in the ways of the Force and mastered lightsaber combat. Finally, she has already duelled Vader and survived it (end of Rebels Season 2).

That makes her a more powerful (than Leia) candidate to defeat Vader, as Leia is untrained, and there is no one left alive capable of training her.

upd: she IS alive by the end of RotJ, according to the Rebels finale.

However:

1. (out-of-universe) Ahsoka character was not even conceived at the time the Original Trilogy was created, making it a retcon
2. The Skywalker twins were purposefully hidden by Yoda and Obi-wan, as the last hope to restore the balance to The Force. In Revenge of The Sith, they speak of no one else.

Thus, it is only a fan theory.