I built a fleet named after figures in Norse mythology. I was pretty meticulous in keeping a unified style across all ships, ranging from the Viking starfighter all the way up to the titan, Odin.
If you want to face these ships as random spawns in bounty mode, check out my mod: https://forum.cosmoteer.net/d/1510-asgardian-armada-new-challenging-enemies-in-bounty-mode
FULL FLEET
ODIN - titan
THOR - battleship
NIDHOGG - missile battleship
LOKI - advanced battlecruiser (eventually a stealth ship if cloaking makes it into the game)
This one's my favorite. Very fast and long range, but with plenty of firepower. Given time, it can take down pretty much any ship in the game - no matter how large(unless you've got like 50+ missile launchers; point defenses can only do so much).
MJOLNIR - heavy cruiser
My second favorite, because it's a handsome sonofagun.
GUNGNIR - missile cruiser
Okay, they're all my favorites.
FENRIR - destroyer
SLEIPNIR - missile destroyer
MUNINN - frigate
HUGINN - frigate
VALKYRIE - missile corvette
VIKING - fighter