Four people have met their end via Needle so far.
While Arya has caused much more destruction these are people who met their demise by being stuck with the pointy end.
1. The Stable Boy - This one was an accident, but she poked the stable boy in Kings Landing in the belly which killed him.
2. Polliver - While traveling with the Hound a brawl breaks out in a Tavern. Polliver is the one who took Needle from her in the first place and is kindly introduced to the pointy end. They just wanted to eat some f**king chickens man.
3. Rorge - One of the three Arya saved from the burning wagon. He ends up attacking Arya and the Hound and meets his end with another stab in the belly.
4. The Waif - After deciding she is not No One, she is Arya Stark of Winterfell and is going home, The Waif confronts her. The deed is done in the dark after Arya draws Needle and cuts out the candle.
Honorable Mention - Polliver uses Needle to kill Lommy in the Lannisters' attempt to catch Arya and Gendry.
Other Instances of Needle:
- Given Needle by Jon Snow, almost stabs him with it.
- Has to pack it away for the trip to Kings Landing.
- Grabs it on her way out. See #1.
- Loses it to Polliver when they are attacked on their way North.
- Regains it at the tavern with the Hound. See #2.
- Practices with it numerous times in travels with the Hound.
- Must hide it away once she enters the House of Black and White.
- Retrieves it once she decides to leave. See #4.
- Carries it with her ever since on her journey home. Thinks about using it when runs across Ed Shereen.
- Most notably uses it to practice with Brienne once she is back in Winterfell.
Other Killing (so far):
- The Tickler - Not a direct kill but is killed by Jaqen on direct order from Arya.
- Ser Armory Lorch - The second name to Jaqen.
- A bunch of soliders - The third name(s) to Jaqen while they escape Harrenhal.
- Frey Solider #362 - Shortly after the Red Wedding Arya and Hound run into trouble and have to dispatch four soldiers.
- Lannister Soldier #814: Just prior to reclaiming Needle Arya kills this one in the tavern brawl.
- Ser Meryn Trant: While in Braavos Ser Meryn picks the wrong brothel to visit and shanked repeatedly in the face by Arya.
- Lothar Frey and "Black" Walder Rivers - Baked them into a pie and served to Walder Frey.
- Lord Walder Frey - Slit throat after eating his kin.
- All the Freys that matter - Poisoned wine.
- Lord Petyr "Littlefinger" Baelish - Slit throat with Valyrian Steel dagger that was used in the attempt on Bran's life.