Strangely enough, I’ll answer to Lizard.
If I’m writing something (I fancy myself an author, even though I can’t write anything longer than a college essay), I use Christopher. If I’m signing something (like a reciept) I’ll use whatever I feel like at the time.
Socially, I go by Chris. People do call me Christopher, though, and I don’t really care.
But no matter what, unless you’re an authority figure, you may not address me by my last name only.
My birth certificate says Michelle, but until I was in the Navy, I went by Mickie. When I was almost 20, I started dating a guy who didn’t like nicknames, and he insisted on calling me Michelle. I was young and foolish and he was cute as can be, and I’ve gone by Michelle ever since. A few family members and old friends have a difficult time with the change (it’s just been 28 years after all) but I don’t generally tell new acquaintences about my nick. Just don’t call me Chellie… please…
My name is Jay. There’s no way to shorten it, so I don’t mind answering to Jason or any other variation that you can come up with. There are exactly 0 people in the universe who can get away with calling me Jaybird.
Whenever I hear ‘Christopher’, I immediately stop what I’m doing and think I’m in trouble for something. It’s almost a unconscious Pavlovian response to hearing my parents say that when I was a kid. Hearing ‘Christopher’=Trouble. Big trouble.
The worst part of that is that different girls I’ve dated through the years have noticed that when they call me ‘Christopher’, I immediately start listening to them and genuine seem concerned about what it is they’re talking about.
I hate it.
Partly because it works, and partly because they’ve been able to figure out a way to unconsciously, and outside of my control, figure out a way to make me act.
Let’s just say it’s something I’m working on.
My name is Kriss and some people mistakenly call me Christopher. I’m a pretty good size fellow so not many have tried calling me Krissy.
My full name is Alexander. I’m almost exclusively known as Alex. (Except for several IRL friends from college who still call me Cliffy.) I don’t let anyone call me Al except my dad and my old roommate. (It was a trade-off; I was the only person allowed to call him Dyl.)
–Cliffy
P.S. We refer to my sister’s friend Lauren as “Lo.”
No, I am a Kathryn, but I use Katie. I didn’t really choose it, my parents did I guess, and everyone has called me Katie ever since.
My name is John, but online I usually go by JOhn. 
(It’s a boring story, and I’ve already posted it somewhere on SDMB, and no, I don’t feel like looking it up for you :p)
I once had someone insist that my full name must be Jonathan (or some variant spelling thereof), and would not accept the fact that my parents named me simply John. Strangeness.
I do not disclose my middle name to anyone. (Well, my sweetie knows it and maybe one or two other people, but they have to find it out for themselves.) Much like other posters’ full names, the use of my middle name immediately puts me into “oh, shit, what did I do?!?” mode.
I do have some relatives that insist on calling me Jackie for some gawd-awful reason. I’ve been told it’s a mid-west thing, but I have my doubts.
Fun thread!
JOhn.
I find it interesting that both my name and my brother’s name both have seven letters, but while there are many accepted dimitives for his name- Vincent- there are none for mine- Shannon. Only a couple of people have tried shortening my name, but gave up on it because everything they could come up with sounded so akward, a thing for which I’m glad indeed. My Uncle, though, is named Don. It’s not his nickname, it’s his actual name. No one is quite willing to accept that, poor guy.
Mostly I go by Stephanie, but a few people call me Steph. I don’t mind it.
Unless…I don’t like you. Then it seems a bit presumptuous for you to call me Steph.
Right now I can only think of one person that bugs me with that. And he’d probably bug me no matter what he called me.
So Rue, you can call me Steph. Or Scout. Just don’t call me late for dinner.
ba dum bum.
I go by the full thing, Lorna. My sister wanted to call me “Elle” for a while, but that never worked.
At work I go by my last name. When I was hired the manager forgot that there was all ready an employee with my first name, it’s common. His response was “Lets use your middle name”. My retort was “Two (first names) is confusing but two (middle names) aren’t”? His first name was my middle. I’ve gone by my last name for twelve years now.
My first name is short. I do use it in full. Only my sister is allowed to make it a dimunitive by adding a y. I get to call her my little sister instead of younger sister. It’s a trade.
This is an Iss-yeww for me.
My first name is Christian, which my parents gave me because they liked the name Chris and didn’t much care for Christopher. Christian also worked well with my very common, but vaguely Scandinavian last name.
And it was good. But then I came in to the wider world, where I realized not only that zillions of people were named Chris, but that half of them were female. And an astonishing number of Chrises of either gender share my last name, which is a Major PITA.
In defense of my parents, Chris wasn’t a common American name until somehow it was was “discovered” in the 60s. The only Chris I know who’s my parent’s generation is a German friend of my father’s. So they tried.
Anyway, by college I’d decided that it was time to go by Christian, if only to avoid having problems with mail and bursar’s accounts. Good thing I did - even at a college of 1800 students, two of them were Chris _____. Christian worked OK. Kinda fit with the gay “only-by-our-full-names” thing.
Then came law school and my first mass mailing of resumes part of an almost-futile attempt to secure a summer job as a first-year law student in 1992. My resume listed me as Christian P _______.
At least a quarter of the rejection letters came addressed to “Ms. Christian Johnson,” and that disturbed me. I blame Night Ranger. (It’s especially hateful since (a) IIRC the songwriter’s sister was named Christine “but that didn’t fit in the beat,” and (b) the song basically says, “Hey, sis, I love you but you’re a big slut and I wish you’d stop it.”) Professionally I now go by Christian Peter, at least for the first contact.
And now I’m not thrilled with Christian any more. I never really objected to Chris, so everyone who knew me before 1986 continues to use that. What I like, actually, is CJ, something a dear friend from college uses. Time for a switch?
I’m addled. Why do I even try? Why? Okay, so it’s Christian Peter Johnson. And that’s the real kicker (as a law school friend helpfully pointed out: 2/3 of it is synonymous with “penis.”
Theo, not Theodore, for relatively obvious reasons. If you say my full name out, “Theodore David McLauchlin,” you get this sudden urge to add a “the third.”
Oh, speakin’ of which… My school’s debating union has this guy called Jesse, a management student who carries around a business card… (“Jesse McWaters, Student of Management.”) Because of his pretensiousness, my debate friends and I started calling him–purely in jest, he’s a good friend–“Jesse McWaters III”, and he dug some stuff up and actually found out that he is III, technically… His full name is Robert Jesse McWaters, his dad is Robert Joseph McWaters and his grandfather was Robert James McWaters. So he now goes–for the purposes of debating–by “R. Jesse McWaters III.”
Too bad he isn’t in Law.
My name is Rachael. It’s Rachael, darnit, just Rachael. For some reason people always assume that once they’ve known me an hour or two, they can shorten it to Rach (pronounced “Raych”). Words cannot describe how my skin crawls when someone says “How you doing, Rach?” My parents are the only ones allowed to call me that, and that’s under protest. I now tell people that if they must shorten my name, they can call me Rae. Never Rach.
The most irritating thing about the name-shortening trend is that it always seems to be my supervisor at a given job that decides to call me by the hated short form of my name. I’ve found that it’s very awkward to politely ask your boss not to shorten your name when they’re obviously trying to be friendly and cool, and you certainly don’t want them to go to the other extreme. After five years in the workforce and several bosses who all follow this pattern, I’ve learned to just grin and bear it.
But one of these days I’m gonna go postal. Grrr, and stuff.
I suck for forgetting to put this in my last post:
An ex-boyfriend’s given name is Robert. He so loathes any and all variants of that name – Rob, Robby, Bob, Bobby, etc. – that rather than suffer any foreshortening, he has gone by Mouse since he was fourteen. The fact that he rather looks like a Mouse makes this easier to understand, and easy for folks to remember to call him Mouse instead of Robert.
Well people could call you Egg. Which you could take as a compliment claiming it’s cause you’re so smart.
I have almost never been called by my full first name, instead going by a nickname. In fact If you were to call me Osiris a couple of years ago I might not even have turned around. But I got tired of explaning 1)How to pronounce my first name and 2) that I don’t really use it and you can use this one instead. So now 1 person I know does. Took awhile to get used to it.
Ditto for me. I would only offer one variation on the theme and that is that my mother, and only my mother, can call me Craigy. Unfortunately, she does this quite frequently. I don’t like it, but she’s my mom, so what can I do? I should note that my wife does not enjoy the Craigy exemption. She does, however, call me “rocky crag” from time to time since she read in a name book that this is the Welsh definition of Craig.