Ronan the Accuser was the main antagonist of Guardians of the Galaxy, but audiences were also treated to an appearance from Thanos in the film. The Mad Titan was seen chilling in his space chair ordering Ronan to find an Infinity Stone, but that was the only time he showed up in person. Thanos may be the Marvel Cinematic Universe’s big villain who will be tearing it up in the Avengers: Infinity WarGuardians of the Galaxy, he didn’t serve much of a purpose. It turns out the director of the movie shares that sentiment.
During an interview with Vulture, James Gunn revealed that the hardest scenes to write in the film were the character introductions, specifically because they kept changing during different points of the creative process. However, the character proved the most difficult challenge overall was Thanos. Said Gunn:
"There’s pressure with Thanos because you’re setting up this gigantic character that, in one way, isn’t really a part of your movie. His presence doesn’t really serve being in Guardians, and having Thanos be in that scene was more helpful to the Marvel Universe than it was to Guardians of the Galaxy. I always wanted to have Thanos in there, but from a structural standpoint, you don’t need him."
What Gunn seems to be saying is that while it was great to be able to throw the Mad Titan into the mix, he wasn’t actually necessary to the overall plot. His main function was just to remind viewers that Guardians of the Galaxy takes place in the Marvel Cinematic Universe. Many have compared Thanos’ appearance to Emperor Palpatine’s debut in The Empire Strikes Back, in that it set up the character as a dangerous foe without having him get directly involved. We’ll be seeing Thanos shine in Phase Three, but for now he’s taking a back seat to the other villains in the MCU.
Gunn also mentioned that he wanted to make sure that including Thanos didn't "belittle" Ronan, as he didn't want the scary central antagonist of his film to "seem like a big wussy" bowing down to a greater power. Fortunately, this was accomplished. Although the Kree warrior wasn’t as well-developed as the other characters in the film, he was clearly established as someone not to be trifled with. We see this when he snaps The Other’s neck (a character that even Loki was guarded around), and later when he slams the Power Stone into his hammer and heads to destroy Xandar. He may not have been the most captivating villain in the MCU, but he was certainly established as one of the more powerful. That being said, I have doubts whether he would have been able to kill Thanos as he threatened, even with the aid of an Infinity Stone.
