I beat SMB3, SMB, Ice Hockey (You can technically do that by beating everybody), and Zelda.

I remember beating a lot of NES games back in the day, probably too many to recall but I'll list some that come to mind
-Castlevania 1-3
-Mega Man 1-6
-Metroid
-Zelda
-Bucky O'Hare
-Mario 1-3
-Final Fantasy
-TMNT 2
-Crystalis
-Super Contra
Dude I personally think NES has some of the most difficult games out of any system.

The games I only beat was th Super Mario series. Pathetic isn't it? :p

Oh yeah, I've beaten several. Off the top of my head:

SMB 1-3
FF1
Pro Wrestling
Contra
Rampage
Mega Man 6
Monster Party
The Legend of Zelda 1 & 2 (#2 via ROM)
Battletoads (using a ROM and save states)

There are probably more that I can't remember at the moment.

The only one i ever beat was Contra

i also beat super mario bros. but i cheated

Anyone ever beat Contra without the cheat code? It's impossible. That game was impossible. And saying you beat Battletoads, even with save states, is like saying you beat Ghosts 'n Goblins. Impossible without Game Genie.

I beat a bunch of games. I won't even try to name them. I grew up with an NES.

i've only beaten 1 NES game i can remember, and technically it wasn't on the NES. it was a modified super mario bros. called super mario bros. crossover.

I beat Contra, Mario 1 and 3, Mega Man 1 and 2, Bubble Bobble, Zelda 1, and Metroid.

I've never beaten an actual NES game. I did beat a hack of Super Mario Bros called Super Mario Bros Crossover.

The Nes games i beat are Kirby Adventures, Super Mario Bros 1, & Mike Tyson's Punch-Out!

I haven't played too many NES games but I have beat SMB3.

I have beat the first Megaman and the first zelda. I got to the last level of ninja gaiden (hardest game ever!) but died on the last boss.

I beat SMB, SMB2, Contra, and Mega Man 2

I beat contra and SM3 and im very close to beating final fantasy 1&3(suck at two)

Well, no not entirely, when i would go over to my cousins house we would play Mario on his NES but we never ended up beating which makes me sad.

I have personally beaten:

Mega Man (1-6)
Castlevania (1&2, though I was lucky beating 1)
Super Mario Bros.
Metal Storm
Street Fighter 2010: The Final Fight (Just beaten 5 mins ago and I'm still pumped about it)

I too grew up with NES, so the list is long. Lucky for me, I still own the NES and almost EVERY game I owned for it, and there are very few that I rented and did not end up owning. That makes it easy to list them all. It was kind of nice to get them out of the shelf and list them. I will also count the ones I got through Wii channel. I won't count games I only beat on emulators with save states because that is not REALLY beating it. I also never owned a game genie before, so please don't throw that at me.

Castlevania 1-2
Super Mario Bros. 1-3
Mario is Missing
Metroid
Faxanadu
Battletoads (Despite what many say, if you play it enough like I did, it gets to the point
where there are only 5 levels that are hard. But those five are still
ridiculously hard. Just keep the 'liar' comments to yourself, because you are
wrong. Did not use a ROM because I still own the cartridge. I just know this
is the one that people are going to want to call me on )
Battletoads & Double Dragons
Fantastic Adventures of Dizzy
Dizzy The Adventurer
Rush n' Attack (Only beat it once. Way harder than battletoads)
Phantom Fighter
Dragon Spirit
Snake Rattle n' Roll
Nightmare on Elm Street
Friday the 13th
Ninja Gaiden 1-3
Bram Stoker's Dracula
Werewolf: Last Warrior
Megaman 1-6
Crystalis
Zelda 1-2
Bases Loaded 3
Teenage Mutant Ninja Turtles
Teenage Mutant Ninja Turtles II the Arcade Game
Tom and Jerry
Rocky and Bullwinkle
Little Mermaid (shut up)
Bubble Bobble 1-2
Jurassic Park
Who Framed Roger Rabbit
Kirby's Adventure
Warrio's Woods
Mike Tyson Punch-Out
Contra
Big Nose
Little Ninja Brothers
Kid Icarus
Robin Hood: Prince of Thieves
Monster Party
Spiderman: Return of the Sinister 6
Adams Family
Adventure Island
Archon
Batman: Return of the Joker
Battle of Olympus
Battleship
Double Dribble
Exitebike (got through all courses)
Ghostbusters
Ghostbusters II
New Ghostbusters II
Gremlins II The New Batch
Home Alone 1-2
The Incredible Crash Dummies
Jaws
Kickmaster
Kid Niki: Radical Ninja
Kung Fu (technically I guess since it just loops around and around)
Lemmings
M.C. Kids
Ninja Crusaders
Paperboy 2
Robocop 1-3
The Simpsons: Bart vs. the Space Mutants
Bart Meets Radioactive Man
Star Wars
Star Wars: The Empire Strikes Back
Superman
Terminator 2: Judgement Day
Tiny Toon Adventures
Super Spike Volleyball
Startropics 1-2
Where's Waldo
Willow
Yoshi's Cookie
Dr. Mario
Kiwi Crazy (hard)

There likely a few others that I know I rented that I can't remember the name to, so I did not try to list those. There are a few that I owned that I let my older brother take with him that I don't remember, but I think I can stand not adding them to the list (Unless I remember them later)

Man I wish I still had all the games I used to have for NES, I have beaten Mega Man 1-6, ninja Gaiden 1-3, Rescue Rangers, Code Name Viper, Tail Spin, Darkwing Duck, Mario Bros 1-3, Astanyax (weird game), wizards and warriors, G.I Joe, Kirby adventures, Tiny toon adventures 1-2, Paperboy, Metal Gear ( my brother and I did that one jointly ) Zelda 1-2, Teenage Mutant Ninja Turtles 1-3, and I know that are tons more but I am not able to figure out what ones I am missing but it was a good trip down memeory lane.

Yes I have. I beaten Super Mario Bros. 2 & 3 and Final Fantasy 2.

i probably beat megaman 6 and the super Mario series a long time ago