Trying to make a spartan fighter worthy of King Leonidas from 300. And how to make him not boring by wielding a spear and sword. Would it be more barbarian like with rage or fighter with the prowess and battle smarts. Really cool idea please help.

Could someone direct me to a good homebrew spartan also

I think barbarian might work better if you’re going for the movie version, because I seem to remember them being unarmored. Like, put a shirt on, dude. So for that vibe, barbarian with spear and shield, since they had those big ass shields fits well, and you can still rage and use unarmored defense with a shield. And it’s easy enough to carry a sword as well. Also, I remember them getting hit a lot and shrugging off the damage, and screaming, so much screaming. So, again, barbarian.
Typically, you see barbarians with heavy weapons, but there no reason you need one. 
If you’re using the spear a lot, the obvious choice for a feat would be polearm master. Which you can use with a shield, even though it’s kind of silly, and you won’t be able to when the new rules stop next year. But for now, spear, shield and polearm master is a pretty solid combo.
If you want do some more fighter-y tricks, you can always take the martial adept feat for a couple battle master maneuvers. 

The problem is going to be you’ll want the asi for str and con, so you won’t likely have a chance for both of those feats. You could go vhuman for race and start with PAM, then you might be able to take martial adept after all. But really, you’ll want to boost con, since it helps hp and ac, and str so you hit more reliably, 

Spartans were the most highly trained and disciplined soldiers of their day. Definitely fighters, not barbarians.

Barbarian for flavour or Fighter for realism

Quote from Arek_the_Cleric >>

Trying to make a spartan fighter worthy of King Leonidas from 300. And how to make him not boring by wielding a spear and sword. Would it be more barbarian like with rage or fighter with the prowess and battle smarts. Really cool idea please help

As most pointed out, barbarian and fighter can meet the Spartan needs. Historically accurate Spartans are going to definitely be fighters and the movie 300 Spartans most fit the barbarian both in flavor and mechanics.

I would say Zealot Barbarian would be a good fit. Spartans had a reputation of being nigh unkillable descendants of Hercules. Zealot is a big pain in the butt to kill and supposedly has damage output that can compete with Berserker damage averages. Plus the zealous presence is fitting for Leonidas' epic scream in the final fight. Unarmored defense works with shields, so you can use a spear, shield, and sword with ease for that full thematic look. Personally, I would take a polearm and greatsword, keep the shield around basically for the look (you can't use it with two-handed weapons), and take Great Weapon Master, Polearm Master, and possibly even Sentinel if your game lasts long enough. V. Human is an easy choice for those feats, but MotM's Orc is pretty choice for Relentless Endurance and Adrenaline Rush... more hit points and more resisting unconscious because why not?

If you can't have fun with those options, can you even call yourself a Spartan?

Historically speaking, Spartans also wore a full panoply, the equivalent of plate for their day.

I would say something like...a multiclass of Wolf Totem Barbarian 4+ for granting advantage to your allies, then Battlemaster Fighter 4+, with the Protection Fighting style, can be an accurate build-type.

Quote from IamSposta >>

Historically speaking, Spartans also wore a full panoply, the equivalent of plate for their day.

 True. But the OP is specifically asking about the version from the movie 300. Or maybe the comic the movie is based on, not sure there. And in the movie, it’s a lot of bare chests. 
I don’t know enough about the comic to say what the art style was there. 

Quote from Xalthu >>

Quote from IamSposta >>

Historically speaking, Spartans also wore a full panoply, the equivalent of plate for their day.

 True. But the OP is specifically asking about the version from the movie 300. Or maybe the comic the movie is based on, not sure there. And in the movie, it’s a lot of bare chests. 
I don’t know enough about the comic to say what the art style was there. 

 
The movie was pretty accurate to the comics.

Quote from IamSposta >>

Historically speaking, Spartans also wore a full panoply, the equivalent of plate for their day.

 Yep. I read that really the only equipment difference if they stood next to any other Greek soldier was their crimson cloak. To me, that screams fighter (the plate armor, not the cloak).

If we were to build a historically accurate Spartan, I might do Battlemaster as an obvious option, but I also might consider a Psi Warrior. Their features are very fitting mechanically and can be flavored to remove the psychic theme for the most part.

Thanks for the help everyone. made a homebrew spartan based off of most suggestions and other homebrew spartans that i liked, i am going to leave the link here. Thank you Erik soong, IamSposta, Xalthu, StylesStriker, and Blackbear for your input.

https://www.dndbeyond.com/subclasses/1887599-ancient-spartan