I am in the works of designing a game and I want to add some easter eggs. For example, one of the eggs is that when the player finds this hidden area they get to meet the "grand cosmic owl". This experience is very brief and made for kicks. Thing is, "the grand cosmic owl" is a cartoon show reference from Adventure Time. Do I need licensing to use their character?

I know games such as zelda easter egg mario and mario games may easter egg Samus aran. I assume its because these characters are all Nintendo.

Asides from a cartoon show character, what about book characters, movies characters, etc...? Also, I am looking to monetize of my game.

I'm not a lawyer, but you seem to have a defensible position. I might have misused the tool, but it doesn't look like 'grand cosmic owl' is trademarked, so it's just a copyright thing. They have copyright to the creature, but if you draw your own version, you should have a strong 'de minimis' case. If you parody Adventure Time in the scene, doubly defensible.

That said, fair use is an 'affirmative defense', meaning if you're sued you can go to court and argue fair use, but you do actually have to go to court and make the argument. Thus it may be the case that you're in the right legally, but would you really want to hire a lawyer and get that affirmed in the court if push comes to shove? If not, it's probably easier to cut out the easter egg.

Do I need licensing to use their character?

Yes.

There are very few exceptions to copyright and trademark law. Many game developers seem to think that the parody exception means any attempt at humor. It does not. Parody is an extremely narrow defense and it does not apply to 'Easter Egg' type content.

Why don't you guys think this qualifies as de minimis usage fair use? Doesn't seek to supersede Adventure Time, doesn't have any clear effect on Adventure Time's value, is low in amount and substantiality (if using custom graphics), seems relatively transformative in that it's an alternate depiction in an alternate media. Content hidden away, not intended to be seen by regular players seems like a pretty de minimis "the law doesn't deal in trifles" usage. Since "Cosmic Owl" doesn't appear to be trademarked, this would strictly be a copyright thing.

Again, there's the practical aspect of do you want to worry about defending, but I find the question an interesting one and would be interested to hear why people think it clearly falls outside of fair use.

It's a different scenario, but here's an interesting article I read a while ago by a person who came up with a game idea (you have a hand of cards referencing pop culture characters, and have to explain why one of yours is the best romantic pairing with a target card), didn't build it (everyone said you'll be sued), and eventually somebody else invented the same game and did build it (de minimis fair use)

http://boingboing.net/2014/06/30/the-card-game-we-couldnt-mak.html

Why don't you guys think this qualifies as de minimis usage fair use?

It doesn't qualify because it isn't the least amount possible.

In this case, the least amount possible is ZERO. There is no need for the IP to be in there at all.

The element is thrown in gratuitously. As an 'Easter Egg' it is content that is not essential to the game, it just happens to be an inside joke to the people who happen to find it.

Now if it were a proper parody that would likely be covered. But that would require using the characters to make a strong narrative about Adventure Time, maybe pointing out some absurd element of the show, or doing some other commentary. But even then it must be kept to a reasonably low level of use, only using what they need for their social commentary.

Alternatively, if part of the game included making a list of top characters then de minimis use might mean only their names and not their picture, or using only their picture for nominative uses.

But what was described is not either of those. It was throwing in an element from another product not because it is essential for commentary, not because it is a parody of Adventure Time, but because they hope using the other company's IP will adds value to their own. And that requires licensing.

Why don't you guys think this qualifies as de minimis usage fair use?

It doesn't qualify because it isn't the least amount possible.

In this case, the least amount possible is ZERO. There is no need for the IP to be in there at all.

The element is thrown in gratuitously. As an 'Easter Egg' it is content that is not essential to the game, it just happens to be an inside joke to the people who happen to find it.

Now if it were a proper parody that would likely be covered. But that would require using the characters to make a strong narrative about Adventure Time, maybe pointing out some absurd element of the show, or doing some other commentary. But even then it must be kept to a reasonably low level of use, only using what they need for their social commentary.

Alternatively, if part of the game included making a list of top characters then de minimis use might mean only their names and not their picture, or using only their picture for nominative uses.

But what was described is not either of those. It was throwing in an element from another product not because it is essential for commentary, not because it is a parody of Adventure Time, but because they hope using the other company's IP will adds value to their own. And that requires licensing.

De minimis means "too trivial to merit consideration", not the least amount possible.

Futurama has frequent star trek homages, and featured a beholder in a brief cameo. Parks and Recreations built a prop iron throne from game of thrones, and a character purchased and wore a batman outfit. Family Guy frequently references other television shows in non-parody fashion.

To my (again, not a lawyer) reading a minimal, inconsequential reference is protected and the use of copyrighted characters in tv and movies seems to bear that out. It's a gray area you might have to defend, and lawyers are expensive, so there's a practical reason to be strict, but I don't think other media bear out the idea that any non-parody or non-nomative usage is strictly forbidden.