@Tevish you got it.

I'll try to do an easy-medium-hard run again. Difficulty rated by how obscure I think the media/entity is in this crowd.

Easy

Titular Location
Legendary Land
Titular Location enters the battlefield tapped unless you control a creature or vehicle with flying
: Add one mana of any color.
Ancient Relics -- , : Put the bottom card of your library into your graveyard. If it's historic, you may cast it without paying its mana cost. Otherwise add five mana of any one color.


Medium

Malevolent Monarch

Legendary Creature - Human Noble
When Malevolent Monarch enters the battlefield, choose a creature type.
If a creature of the chosen type you don't control would die, exile it with a collection counter instead. Then, if Malevolent Monarch is on the battlefield, there are no creatures of the chosen type you don't control on the battlefield, and there are four or more exiled cards with collection counters on them, you win the game.
1/3


Hard

Major Antagonist

Legendary Artifact Creature - Human Scientist
Cyberworld Incarnation -- , : Create Major Antagonist's Avatar, a legendary X/X black Avatar Artifact Creature Token. Major Antagonist phases out until that token leaves the battlefield.
0/1


Bonus Easy-Medium entry I thought up while fishing for my hard one. Might be a rough guess since the text came out so simple though.

Titular Item

Artifact
, : Planeswalk, then Chaos Ensues.

That is Correct!

I'm going to chalk this one up to bring semi-obscure, or at least old enough that it's sunk out of the public consciousness.

Game Protagonist
Legendary Creature - Vampire Wraith
Lifelink
When a creature dealt damage by ~ dies, put a number of +1/+1 counters on ~ equal to the life you've gained this turn.
If ~ would die, remove all +1/+1 counters from it instead. If you cannot, exile ~.
[2/2]

I might decide to create a companion card, but outside one solid idea, I have to work out what to do.

one from the same universe as this:

Deceitful Dominator
Creature - Devil Advisor
: You may put a -1/-1 counter on target creature. Then, gain control of it if its power is less than Deceitful Dominator's.
3/3

Titular Creature
Creature - Egg
Lifelink
Whenever you gain life, put a +1/+1 counter on this creature.
As long as this creature's power is greater than 0, it loses the egg type and becomes an alien that gains flying.
As long as this creature's power is greater than 5, it loses flying and gains first strike and ward .
[0/3]

From the same game:
Herald of the Apocalypse
Legendary Enchantment Creature - Horror Noble God
Indestructible
At the beginning of each player's upkeep, you may destroy target permanent. If you do, that permanent's controller reveals cards from the top of their library until they reveal a card that shares a permanent type with it, puts it onto the battlefield, then puts the rest on the bottom of their library in a random order.
Herald of the Apocalypse isn't a creature unless there are 10 or more permanent cards in graveyards.
6/6

Heroic Slayer
Legendary Creature - Bird Knight Assassin
, Sacrifice Heroic Slayer: choose one:
-Target legendary permanent's controller sacrifices it.
-Return target legendary creature card from your graveyard to the battlefield.
2/2

Antagonist
Legendary Artifact Creature - Scientist
Defender, Deathtouch
If a creature you control attacked or blocked alone, when it dies this turn, assemble a contraption.
, sacrifice a creature, sacrifice a contraption: Investigate twice.
Sacrifice 20 clues: Create a Food Token and you win the game.
[10/10]

An adventuring party

Party Cleric
Creature - Human Cleric
: Create a 1/1 colorless spirit creature token.
Sacrifice Party Cleric: Creatures you control gain indestructible until end of turn.
2/2

Party Mage
Creature - Elf Wizard
You may cast one creature spell from exile each turn and you may spend mana as though it were mana of any color to cast it.
2/2

Party Warrior
Creature - Human Warrior
Whenever you cast a nonhuman creature spell, put a +1/+1 counter on Party Warrior.
: Party Warrior fights target non-human creature.
2/2

Party Barbarian
Creature - Dwarf Barbarian
Whenever a creature an opponent controls dies, create a food token.
Sacrifice a food token: target creature gets +2/+2 until end of turn.
2/2

Party Rogue
Creature - Halfling Rogue
Triggered abilities of permanents your opponents control don't trigger.
Your opponents can't cast spells without paying their mana costs.
2/2

Going to guess

and Barinellos gets it!

Prescient Bladesmith
Legendary Creature - Human Artificer
Play with the top card of your library revealed. You may play the top card of your library as long as it's an equipment.
When you control 12 or more equipment, you win the game.
3/3

From another franchise entirely

Ace Defender
Legendary Creature - Human Advisor
Ward
: Change the target of target spell or ability to Ace Defender.
2/2

I feel like I should be getting the Bladesmith, but it isn't surfacing in my mind.

The other, on the other hand:

And Barinellos gets it again!

These are from different shows btw

Emotionless Arbiter
Legendary Creature - Homunculus
If another creature would die, you may put it on top of its owner's library instead. If you don't, exile it instead.
Damage that would reduce your life total to less than 1 reduces it to 1 instead. When damage is prevented this way, you lose the game at the beginning of your next end step.
4/4

Enforcer's Armament
Artifact - Equipment
Equipped creature gets +3/+0 and has first strike as long as it's blocked by or blocking a nonwhite creature.
Equip

No guesses, but how about something for you all to guess?

All the same franchise, but not necessarily the same installment in that franchise:

Film Antagonist
Legendary creature - Human Assassin
First strike, reach
Whenever a creature an opponent controls dies, it was dealt damage or targeted by ~ this turn, create a Gold token. (It’s an artifact with “Sacrifice this artifact: Add one mana of any color.”)
4/2
(this should really be a heck of a lot more than one gold token, but I want this to seem somewhat printable)


Famous Movie Weapon
Artifact - Equipment
You may cast ~ by tapping five artifacts you control named gold instead of paying its mana cost.
Equipped creature has reach, death touch and ", sacrifice an artifact you control named gold: Destroy target creature".
equip


Film Antagonist
Legendary creature - Human Citizen
As long as other players have a total of 5 or more rad counters, artifacts named gold you control have, "Sacrifice this artifact: Add three mana of any one color.”
Whenever one or more creatures you control deal combat damage to a player, that player gets a rad counter for each artifact named gold they control.
2/2

Any guesses?

Same franchise than above

Recurring Film Antagonist
Legendary Creature - Human
When ~ enters create a 1/1 white cat creature token.
Trap spells you cast cost less to cast.
At the beginning of your end step, for each creature you control that dealt damage to a creature another player controls, sacrifice that creature if the creature it dealt damage to didn't leave the battlefield this turn.
1/1
That word salad up there is just to say that this character, famously does not tolerate failure.


Film Protagonist
Legendary creature - Human Rogue
Reach, protection from traps
When ~ enters the battlefield, secretly note the names of up to three equipment cards. Whenever ~ attacks or blocks, you may cast a card noted this way as though it had flash. If you do, when that equipment enters the battlefield attach it to ~.
3/2

For the previous two posts

@Neru can you please put your guesses in spoiler blocks?

Amateur Artillerist
Creature - Human Mercenary
Vigilance
: Expert Artillerist deals 1 damage to target creature. That creature gains flying until end of turn.
2/2

Free-Spirit Flamer
Creature - Human Mercenary
Wither
: You may choose new targets for a spell that targets a permanent you control.
3/3

Sadistic Surgeon
Creature - Human Mercenary
: Prevent the next 1 damage that would be dealt to any target this turn. When damage is prevented this way, put a charge counter on Saidstic Surgeon.
: Target creature gains indestructible until end of turn. Activate this ability only if Sadistic Surgeon has two or more charge counters on it.
2/2