Unfortunately, Transformers. :-/
Dear God… Remember when the top grossing movie of the year used to be The Dark Knight? Man, those were the days! =P

I too think Avatar has a big shot to be huge, maybe even 'huger' than Transformers, but we just don't know much about this movie to form an opinion. And most people don't even know this movie exists yet! Fox better start showing something…
So far, only movie geeks are talking about it.

2007 was a bad year for Transformers to come out; there were three trilogies ending, one of which was an family-friendly animated movie, plus add the fact that it came out late in the summer and I think that's why it was number 3 at the end of the year, had it come out earlier it might have been number one.

I have a feeling this is Transformers' year, Terminator will be big, so will Harry Potter, but I have a feeling sex appeal, explosions and humor will propel Revenge of the Fallen to the top this year.

I'd love for it to be either Terminator or Avatar, but as of right now, I think it'll be Transformers. Mega-popular, appeals to all ages, and a blockbuster sequel. Terminator may be too dark for some 9 and 10 year olds that will be able to see Transformers.

If Avatar is truly as revolutionary as it is said to be, then it'll become the top film. However, w/o a poster or trailer, its not sensible to predict it.

Christian Bale isn´t too well known – people know him as "Batman", not as Bale, and he was overshadowed by Heath Ledger in the last movie. Actually, I think T4 is a potential first flop…just a feeling.
I think Transformers will get it – too bad. I think it´s "fun" but something with that primitive script should have warning before opening credits :-)

Hmm, Avatar might just be it. However, since it's a December release, will the B.O. counters count the money it will make in early 2010 into the 2009 B.O. tally? If not, it will be either Transformers or Potter.

Much to my chagrin, it will be Transformers 2, which will ascertain a 3rd one with even more visual razzle dazzle and a script that will once again redefine the meaninng of garbage.

@JunJun: That's a good question, does it?

Does Brad know?

Harry Potter get's my vote

Transformers has this. I don't love the first film, but it was fun, and I just feel the heat surrounding this one. Even if it is just a TITCH better than the first film, I see it slamming the 400 million mark. I just don't know one person who will not be seeing this film.

@JunJun and @Eric: It is a 2009 release so it will all count for 2009.

Avatar will change the curse of the world…

Transformers
Harry Potter (hate the franchise)
Terminator

"Transformers" is the safe bet here- the first film did very well box office wise, plus the "common moviegoer" overall liked the last film (which is why word-of-mouth was fairly stellar for that movie- well, at least better than most Michael Bay films). The next film looks like a blockbuster sequel should- louder, sexier, bigger and (arguably) better. I think by just those factors alone, it'll be big, even if it drops off soon after. I'm thinking this'll perform like another franchise film that I wasn't too fond of- Pirates of the Caribbean. I remember liking the first film alot (like I did w/ Transformers) but I wasn't really excited/thrilled to see another film (like I am now with Transformers). Then POTC: Dead Man's Chest went all "Spider-Man" on us, broke the box office opening record (that sure as hell won't happen with Transformers) and became the highest-grossing film of the year. I see that scenario pretty much happening again.

I'd have to think transformers since it does seem like its atleast not any worse then the last one, altho I think terminator could have some potential to surprise, but its not likely.

has got to be harry potter… think about it the books began in the 2001 its been nearly 8-9 years now the demographic that grew up with it is now in its early twenties… i can see this movie shattering all records for the franchise… probably higher gross than the first one even… the action definitely looks top notch… i have always loved the HP movies despite the several departures from book…

nothing gets bigger than transformers, sure terminator salvation, and avatar, will be better than the robot flick, better written, and acted. the problem is avatar doesnt have the audience that the michael bay film does, with one already out, they are just expanding their fan base, and for avatar it will be hard to compete with SFX transformers boasts, infact any of SFX CGI movies in 2009 will have a hard time to keep up with transformers.

I think Avatar is the only one that has the good chance to break $400 million. Transformers will likely be second with $350+ million, while Harry Potter will make around $320 million.

Transformers surely will cross the $350 mil mark and seems to be a safe bet for the highest grossing Domestic movie(HP6 and Terminator Salvation would be just short of the $325 mill mark)… Avatar is a tricky one…. The movie will either be a big hit or it will be a big dud at the Box-Office… I am very optimistic about it though and am hoping that its box-office performance can give serious competition to Cameron's last flick, Titanic… I know its the Heights of Optimism, but then the only man who can do that is James Cameron

@Athar:

Yeah dude, I'm not exactly feeling "Avatar" either, but then again it's hard to gauge awareness, since there have been no trailers or any real hype outside of us internet-ers. The biggest, best, highest grossing films are the ones that appeal to all ages and moviegoers. "The Dark Knight" did well because the kids like the hero, the young adults liked the action/story/main stars, the adults like the deeper story and the meaning behind all the chaos and madness in the story. I don't know too much about "Avatar" yet, but if it's just Sci-fi action in 3D, it won't break the bank, even if Cameron's last film is the highest grossing movie of all time. Remember, unless it has the words "Star Trek" or "Star Wars" in the title, Sci-Fi movies often bomb. Just keep that in mind.

Also, I can see "Harry Potter" taking the crown if Transformers up and bombs on us. A big, big demographic that people tend to ignore sometimes are girls. This is their blockbuster (besides "New Moon" of course). All my lady friends are dying to see this film (like us guys were dying to see "TDK" last year), and the 8-month delay has made the hype even greater. Don't be surprised if HP6 becomes the highest grossing in the series.

UP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

(hopefully)

I see no hope for Terminator 4 being 2009's champion. I'm expecting to hit $60-75 million this weekend (3-day, not 4-day), but I'm also expecting bad holdovers (the reviews aren't promising).It'll be lucky to break $200 million.

I'm going with Transformers 2 with at least $350 million, and maybe even $400 million. Harry Potter 6 I feel may be the second one to crack $300 million, though. And Avatar… I'm finally worked up enough to see it (I kept on hearing about it long before I had any interest). I'm still waiting for a trailer and some more buzz, though.

I think transformers will take the overall box office gross this year right around 375 mil……there is no other film as hyped as this one……

no.2 will either be harry potter or terminator……

the one thing you failed to mention is pirates 3's memorial day weekend record of 139 mil……..i think terminator has real potential to break this record, however barely breaking it, coming in at around 141 mil fri thru monday…….

X-Men, the origin of Wolverine. This will be the biggest hit movie for 2009.

I would love for it to be HP6. It's about time they got number one. As you can tell by my name, I am a HUGE HP fan. I really liked X Men Origins: Wolverine, Star Trek and Up, so I'd be glad if they made it as well. I know almost nothing about Avatar, although I've heard of it before. I hope that it will not be New Moon, as I hated Twilight. Sadly, I think that it will be Transformers 2. I didn't like the first movie, and I always thought that it was overhyped, but people will want to see it. Everyone but me.
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If you are going to see HP6 the day it comes out, copy this onto your next post.

If you liked X-Men Origins: Wolverine, copy this onto your next post.

First, to #23, Wolverine has already been surpassed by Star Trek. I don't care what the opening was, it's going to be considered a total bomb by the industry.
Second, to #9, $400,000,000 is a huge load of cash and I don't think anyone besides you could honestly speculate that in this economy it has even a chance of making that much. Baloney.
Third, to everyone, Harry Potter 5 was at the time the 6th highest grossing movie in history woldwide, (now at #7, check imdb.com) and I can see #6 breaking the top ten at least. Potter had this won before the year even began, and the likes of Terminator and even Star Trek (though I heard it was awesome!) won't be able to shake it. In the long haul, I think even Up will out-gross both of them.