Nasus

You are more than likely 100% going to lose the game after dying once as Nasus becomes too tanky and have ridiculous damage thanks to Riot's Q buff. *Recommed Perma-banning in Platinum+ if you plan on taking Katarina top*

Riven

Dying to her once or twice depending on your current elo can cost you the game so take extreme caution. 90% Loss rate in Diamond.

Darius

Extremely easy to beat early laning phase, but as time goes on you will more than likely end up dying to him especially if he pulls you and runs ghost as there is almost no chance of escaping,

Rumble

General lane bully and will not give you a single ounce of CS without damaging you. Added to the fact that he has a shield and slow you will be in for the worst lane of your life.

Cho'Gath

General katarina counter. He heals too much for her to effectively harass making it nearly impossible to kill him if he decides to build MR instead of AP.

Galio

General counter to katarina as aftershock and damage reduction abilities + CC does wonders against her.

Pantheon

It's Pantheon

Garen

Listed as a lower tiered threat than the others, you should only worry about garen depending on how your opponent is playing him as it will completely swing how your lane will function. (i,e Tradition Tank, Full Lethality, etc.) Otherwise he's just extremely tanky due to his damage reduction and passive healing.

Camille

You can easily beat Camille in lane or get beaten... HARD. Generally speaking, you don't want to many times as her mobility and gank potential can quickly show around the map.

Irelia

Irelia was and still is a lane bully. She is only high up on the threat list as many players don't play her properly, but be warned as losing to an irelia who is decent can make the game drastically harder.

Nocturne

Nocturne is between 4 and 5 in terms of threat. His most lethal abilities are his ult and fear as getting hit with a 3 second fear is almost bound to have you killed.

Jax

Jax is a 100% skill based match up as you must use your knowledge of Katarina's abilities to evade his stun. Not only that but baiting out his ult and waiting for it to finish will give you a huge advantage.

Shen

Facing Shen in lane isn't difficult by all means, he only shines by helping his team survive fights that they should've lost swinging things massively.

Jayce

100% skill match up.

Fiora

As long as you don't eat her passive procs, you will be fine as she has nothing to severely put katarina at a disadvantage other than her W that she must time perfectly.

Renekton

Renekton is between 3 and 4 regarding threat level. Do not get hit with a full rage stack W and make sure not to be baited by his ultimate.

Urgot

Super slow in lane, but if given enough kills he will be annoying to deal with. Focus on dodging his abilities over anything else and this lane will be a breeze.

Illaoi

Just don't get hit with her E.

Kled

Allow Kled to put his W on cooldown before committing to a fight. Also, be care as him losing skaarl will grant him invincibility frames potentially losing you an otherwise won fight.

Gragas

100% skill match up. Body slam is the only ability you 100% have to try and avoid as it will allow him to chain his entire kit on you.

Dr. Mundo

Super easy to beat pre 6, after that he just heals off ult so there's no reason to really commit to killing him without help after 6.

Aatrox

Super slow animations.

Tryndamere

Avoid being slowed and bait his ult out for the easiest lane of your life.

Sion

Overly slow and most players believe they will be unkillable early while playing him. Use it to your advantage.

Malphite

All he's going to do spam Q at you otherwise he doesn't do much else in lane.

Teemo

He's more annoying if anything but you should win.

Ornn

Maokai

Kennen

It's pretty much a mid matchup, you'll pop him eventually.

Yorick

His main source of damage is his Q and if you commit while it's down and dodge his E he really can't fight back,

Gnar

Squishy outside of mega gnar.