This is a great thread! I took a trip down to the memory lane and found some themes that might fit for an antagonist/megafauna:
All Megafauna theme:
Great build up, sense of desperation, when will the monster DIE? The best part starts at around 2:05.
Bubblegum/Ashdrake on the station:
I remember this song from a film called Chicken Little. THE SKY IS FALLING!!
Relaxed antag who's not really focused on getting greentext:
I just want to live a happy shabby life.
An Antag who has a moral crisis whether they should do their objectives or not:
If I get greentext, am I a loser?
Antag with hijack objective and the time has come to execute their flawless plan:
Just according to keikaku.
"Keikaku" means "plan".
Antags with the same stealing objective:
I wish I was this good at fighting. In a video game.
An hour into the shift, when a non-antag trying so hard to defend the station, only to suddenly become the antag themselves:
Just like Ash from Alien!
Vampire (with guns):
Glare...
The Antag that I aspire to be:
WAY PAST COOL.
Antag life is just a ride:
Another ride? Oh alright then.
These are the themes that I think it fits well when playing an antag!
I have some other music in my mind that does not fit the theme of this thread, but I would like to share it with you guys anyway:
Non-antag (schoolgirl) accused of validhunting:
I swear I was at the wrong place at the wrong time!
Finally, when I read declined appeals in the Unban Request:
We fly so ever close to the flame.