Easiest Hero

No, there are "easy" heroes. Knowledge of the game is a given.

Such as Skeleton King, he has one active. Tidehunter. Bounty Hunter. Etc.

SK isn't easy, because in order to do well, you need to be able to lasthit creeps. I'd say the easiest hero is Vengeful Spirit or maybe Sven. Furion is also easy if you jungle it all day and don't help allies.

Hero's with 2 passive are all easy. Or any right click hero like Drow, Sniper. Invis hero's are pretty easy right now mainly because it's beta and people really are trying a lot of new things out and not really playing the game. I've seen a ton of games so far in games I'm riki not a single vision item was purchased or used the whole game.

I agree with sniper on this one. He's not that squishy, has good harass, and really fun to play.

Not to mention that basically all you do as Viper is auto attack, and ulti.

I see Lich as Dota 2's easiest hero to play; spam Frost Nova/Sacrifice (literally spam them), spam Frost Armor mid game. Chain Frost is also a fire and forget ultimate; after Lich gets Chain Frost off in a fight, he is free to die/run away at no great loss to his team. His lack of item dependence is also a plus for players who haven't yet learned how to not die/farm.

Lion and Lich are good picks.. I also recommend Tide Hunter, as his ult alone can make or break a team fight if you have farmed up carries.

Riki Or viper

because of the overpowered escape and slow.

Axe in my opinion is an easy Hero to lear, though he does require an understanding of how to build him both skill and item wise, how to position wiht Blink Dagger and when to use blademail. Apart from that hes very easy to play early game, and has tons of survivability so you can make mistakes, He is an iniator for new people.

Juggernaut Is an easy to learn hero who can get kills very easily and simply and is durable due to an inbuilt magic immunity, and can take some damage with an early stout/poormans
Also requires an understanding of how to build item/skill wise (need to know what items to get if you want to do lots of damage late game) and how to use his skills like his ultimate Omnislash in groups of enemies or single target. He is a Carry for new people.

Lich

OR THE MANLIEST HERO IN DOTA SKELETION KING IS HERE TO TEACH YOU IN THE WAYS OF DOTA
MAKE A MISTAKE? REINCARNATE.
PUSHING BUTTONS IS HARD? ONE ACTIVE SKILL (MAYBE IF YOU ARE GOOD ENOUGH TWO IF YOU BUY ARMLET)
IT'S DIFFICULT TO PLAY HIM? PROTIP: RIGHT CLICK PEOPLE UNTIL THEY DIE
TO CHICKEN TO STAY IN LANE? HE CAN JUNGLE!!!

IF YOU THINK YOU CAN MASTER THE MANLIEST HERO IN DOTA WITHOUT TESTICLES PICK HIM UNLESS YOU WANT RAPED BY HIM