Which Champions have you got pentakills with?
Ive got some with:

im by far the proudest of my
takill.
Ive got some with:

im by far the proudest of my
takill.
I've never gotten a Penta kill, but I have gotten a Karthus on my team one before.
I was jungling Hecarim and the enemy had just gotten Dragon, and 4 of us engaged from bot lane as they were low heath, and attempting to back. Our Karthus was sitting in the pixel brush waiting for us to funnel them to him, he pops his AoE and Wall, slowing the entire team as the teamfight erupts on top of Karthus. He dies, his passive pops, and he starts channeling his Ult. As Hecarim, I ran around the Karthus AoE, ulted 3 enemies back into the Karthus AoE when they flashed out. The rest of my team got destroyed, but as the Karthus Ult finished he killed all but the enemy Caitlyn, who 90 caliber netted out of the Kartus AoE, surviving with 300 health. Luckily, my Charge just came off CD and I knocked her back in for the final tick of the Karthus' AoE, getting him the Penta Kill.
Penta-Assist Achieved.
I'm a support main, so I don't get many, buuut I have got a pentakill with Sona. :D Also, Graves and Quinn!
I am a simple man, so i did only one Penta - but one that mattered
,,/,
,,,/
I am so proud of my 352 Katarina pentakills. Hardest champ to get pentas with imo.
I think I've gotten 2? maybe 3...most of the champs I play (starting to change) excel in skirmishes with only 2-3 possible kills :/, oh well.
The first one was the funniest though. It came in this crazy game where the enemy team picked all cc tanks (mundo, voli, garen, you get the picture) and all took smite. They then proceeded to deathball around the map ganking lane by lane. I was in pretty low elo at the time so it was working for them :P. I was playing kog'maw (like second time) and managed to stay safe and farm it out. So coming into mid game they have a legit gold lead and my team is ready to ff. I was encouraging them that it was ok as I walked up towards top lane to get some farm...and stumble on the enemy team taking an early baron. At which point I just started spamming kog ultis on them with a slow field blocking their exit. There's pandemonium on their end and me+baron got the ez penta. We then proceeded to win the game :D, the entire match and the penta were just so ridiculous I love it.
Penta

upvoted for
takill, hopefully you didn't just add that to be punny
I have only ever gotten 1 penta kill and that was with Teemo.... 
Katarina in every other comment. Who had seen that one coming?
Personal record (ranked):
x3
x3
x2 (Rest in Peace AP Yi)
x1
x1
x1
I don't remember exactly how many Pentas I've done in other game modes, but I rolled
a few times in ARAMs. Needless to say how that ended. :P
too and many others.
My first, only got one with her. :3
It wasn't even with my ult (it was on CD). This was the most glorious Penta I've ever had: It was Legend of the Poro King, we owned the other team pretty hard, I had my Poro Dash/Mark. I was like, "what the hell" and jumped to their fountain with their whole team in it. I died, but as my E got automatically activated with Death Defied on, I basically killed all of them (With a little help of my Q and W). It was f*cking amazing.
Two easy Yi pentas in Aram, though not in the same game (but I did almost got another penta with my first Yi penta).
I got one on the PBE with him, in the Twisted Treeline Hexakill mode (I think that someone stole my Hexa lol). I wasn't sure what's happening though. It just happened. ;D
I'm pretty certain that there were more that I just can't recall at this very moment. (I did get a ton against bots, whether on the live servers, when playing bots just for fun, or when testing new skins in a 1v5 bots custom game on the PBE.)
Very, very proud of my zil penta.
(was my first wooo)
(the old one not the new)
(again old starfall not the new)

My friend has a joke... "If we play all night and Scotty doesnt get a penta, Im disapointed..." We do try and set them up in what ever we're playing. My proudest was the leona.
I only had 2 pentas both of em were with ryze
against five other
's
"Shentakill" oh my god that's beautiful
ANYWAYS
x2
x1
x2
x3
x5 (shhhh)
x1
x2
x1
x1
x3
x1
x2
x1
x2
x1(hit r after a teamfight. Best feeling ever)
x4
x1
x1
x1
Ye
Most proud of my Diana penta. I was 3 levels behind their entire team. I just came out and picked off thier ADC instantly and then killed their APC really quickly and then moved to the tankier teammates and someone ended up killing them all.
My Vayne penta was a 1v5 tho. So yeah. I was SUPER fed just ulted, ran in and started shooting motherfuckers. Somehow killed them all. They ffd soon after.
Ermm.....do bot match pentakills count because I may or may not suck in norms...if so...

Been playing the game for a year and still no penta...

2 as
in Ranked
And 
I got a pentakill as ad fizz 2-3 games ago. But most pentakills would probably be kat or fizz (ad)
I've got 9 on
, 1 on
, 1 on
, 1 on
, 1 on
, 1 on
:p Draven is my main Champion

These are the ones I can think of off hand.

But I'm the most proud of my first pentakill ever.. with the dark lord himself.
<3 The best part is that someone happened to be recording the match. :D [PLEASE IGNORE MY BUILD, I WAS LEVEL 20 OR SO HAVE MERCY] Ending 21/0 :D
PS: A shentakill?! How?!

In order...

Guess which role I main...
So far...
x2
x1
The Warwick one was during an ascension game. Got ascended and somehow got a penta. Was my favorite just due to the sheer confusion from both teams.
I tried very hard to pentakill with Teemo. Never got it. But Fiddlesticks in ARAM and SR, and Sona in ARAM
I don't know anymore it's been quite a few to the point I've let pentas go intentionally to press an objective or victory. It's interesting I dropped one before to get a win over the penta by this very deliberate short term action and had my team scream at me for winning instead of getting a penta. TBH I'm glad they lost their luster for me if it means I'm not throwing games for them. This one was as Miss Fortune, surprised I don't see more Miss Fortune pentas in this thread TBH.