Did Madame Maxime really just have big bones?

Question

In Goblet of Fire it is heavily implied that Madame Maxime is half giant, but never explicitly mentioned.

In The Order of the Phoenix, this is further enforced by stating that she went with Hagrid to meet the giants, not explicitly mentioned anywhere. In fact, I don't think there are even any clues to her giant origins (like Hagrid's tough magic resistant skin), except for the fact that she is huge (which does not seem to be conclusive proof of someone being half-giant, as nobody other than Hagrid seems to bring it up). For all we know she could just be sympathetic to Hagrid's cause.

Is it ever explicitly mentioned that she is a half giant in the books or author interviews?

Answer 1

Like Hagrid, she has some giant blood.

From the Pottermore entry for “Beauxbatons Academy of Magic”:

Headmistress Olympe Maxime is (in spite of her protestations to the contrary) half-giantess; brilliant, elegant and undeniably awe-inspiring.

Alternatively, this issue was hinted at obliquely in a post-Deathly Hallows interview:

Did Hagrid ever get married and have children?

No. […] No, no, Hagrid never did marry and have children. […] Realistically, Hagrid’s pool of potential girlfriends is extremely limited. Because with the giants killing each other off, the number of giantesses around is infinitesimal and he met one of the only ones, and I’m afraid, she thought he was kind of cute, but she was a little more, how should I put it, sophisticated than Hagrid.

— J.K. Rowling at Carnegie Hall, October 2007

This passage must be referring to Madame Maxime, and so we deduce that she is giantess (although unlike Pottermore, this does not confirm that she is half-giantess).

Answer 2

Though never explicitly mentioned, we are lead to believe that Madame Maxine is in fact a half-giant.

This is a tricky one since all we have (from the books) is Harry's viewpoint; and Harry only hears allusions to this issue, and mostly in passing.

But from what he hears, he definitely concludes that she must be half-giant:

“I don’t know who Maxime thinks she’s kidding,” Harry said, watching Madame Maxime sitting alone at the judges’ table, looking very somber. “If Hagrid’s half-giant, she definitely is. Big bones . . . the only thing that’s got bigger bones than her is a dinosaur.”
^{-Harry Potter and the Goblet of Fire, Chapter Twenty-Three (The Yule Ball).}

Given the evidence, and Madame Maxine's reaction to Hagrid bringing the topic up, we can also safely come to the same conclusion:

“Eh?” said Hagrid blankly. “No, don’ go! I’ve — I’ve never met another one before!”
“Anuzzer what, precisely?” said Madame Maxime, her tone icy.
Harry could have told Hagrid it was best not to answer; he stood there in the shadows gritting his teeth, hoping against hope he wouldn’t — but it was no good.
“Another half-giant, o’ course!” said Hagrid.
“ ’Ow dare you!” shrieked Madame Maxime. Her voice exploded through the peaceful night air like a foghorn; behind him, Harry heard Fleur and Roger fall out of their rosebush. “I ’ave nevair been more insulted in my life! ’Alf-giant? Moi? I ’ave — I ’ave big bones!”
^{-Harry Potter and the Goblet of Fire, Chapter Twenty-Three (The Yule Ball).}

Answer 3

Sorry for resurrecting this.

I'm going to say the answer is a pretty clear no. She didn't just have big bones, she was a half-giant.

In The Goblet of Fire, after Harry has his vision, he goes to see Professor Dumbledore and overhears him and Fudge talking about Barty Crouch's death:

'Or else - well ...' Fudge sounded embarrassed. 'Well, I'll reserve judgement until after I've seen the place where he was found, but you say it was just past the Beauxbatons carriage? Dumbledore, you know what that woman is?'

'I consider her to be a very able Headmistress - and an excellent dancer,' said Dumbledore quietly.

'Dumbledore, come!' said Fudge angrily. 'Don't you think you might be prejudiced in her favour because of Hagrid? They don't all turn out harmless - if, indeed, you can call Hagrid harmless, with that monster fixation he's got -'

'I no more suspect Madame Maxime than Hagrid,' said Dumbledore, just as calmly. 'I think it possible that it is you who are prejudiced, Cornelius.'

Harry Potter and the Goblet of Fire - p.503 - Bloomsbury - chapter 29, The Dream