Yes and No.
Words alone like "Hobbes", "Calvin", "Halo", and "Cortana" can not be copyrighted because they are common place words and names. However, combinations of words can be. Words like "Halo 2", "Superman", and "Back To The Future" can. Fully made up words can be trademarked and copyrighted as well. Ungorry would be a great example of that; as would most names of Halo characters and species. But "Grunt", Elite", "Jackal", and "Forerunner" can not. Names of characters like "Bruce Wayne", "Avery Johnson", "Peter Parker", etc can not be copyrighted because they are real names used by hundreds of people.

However, the unique spelling and appearance of names can be copyrighted. But when done, they then fall into the graphical logo category. "Portal" is a great example of this

Sadly, technology and the internet has made naming parodies (true parodies) a nightmare. Parody artist are consistently running into ID bots on a daily bases. These IDbot look at the names, keywords, & tags of all images online. If ANY OF THOSE WORDS match copyrighted material in their databanks, then they create a false claim on behalf of the company in their databanks and have the supposedly infringing art removed. The IDbots completely ignore the art and the rights of the parody artist for the equal rights of the larger artist/company.

Think of it as the same issues we are all having with the IDbot on YouTube type sites. But Parody Artist have been dealing with it for two years longer and on multiple websites. RebBubble has such a bot and is the reason I've stopped using them. Their Bot has removed all of my Portal parodies and claiming Valve made the claims. I've contacted Valve each time and they have denied making the claim. They agreed that the claim was ridiculous after seeing the art in question and wrote a nice approval letter to RedBubble to support my rights. They even went a step futher and promoted the art once it was back up for sale. Needless to say, but that was a good week for me. However, once a claim has been removed from said art, RedBubble does not put any protection on it to prevent future false claims. And the exact same art was removed. I had to go through this process four times because of the stupid IDbot. I got tired of it and moved it to SpreadShirt. None of my other parodies are attcked by the bot because none of them have the word "Portal" in the title. But I can't remove the word because "Dr.Portal" is the best name for the design.

Companies like RedBubble also have the DMCA. This is a group od actual human being going through online art submissions to ensure parodies and art are indeed parodies and/or original works of art. And for the most part, they do their job very well. However, they also get paid on commission which results in them removing parodies during the release dates of the parody's subject matter's promotions. These promotions are game and movie releases as well as clothing releases. Although they have no right to remove parodies, they do so to ensure sales traffic is driven toward the parody subject instead of the parody. This earns them a higher commision (based on traffic flow). It wouldn't be companies like Valve paying the commisions. It'd be the retailers and third party product companies behind it.

Hopefully that was easy to understand.
In short, I have the right to use "Hobbes" in my parody's title. But because of the IDbot, I can't take the risk of it being falsely taken down.