Now, I'll be honest - mine isn't much of a pseudonym as Sedgwick is actually my surname. I probably should have adopted something easier to spell but I'm proud of my roots (according to SedgwickUK.org, the surname is believed to come from old Norse, and the geologist Adam Sedgwick asserted that 'seggeswick' meant 'village of victory'). It also amuses me that James Coburn's character in The Great Escape is called Sedgwick, and he's one of the few characters to actually escape.
However, you probably won't be too surprised to learn Icy isn't my real name. It's actually a nickname that stemmed from an Internet handle I started using in around 2002 that just stuck. When I submitted my first story to a magazine in late 2004, it didn't occur to me NOT to use the pen name 'Icy Sedgwick'. The story wasn't accepted, but when my first story was published online in 2008 (Bending Spoons published The Midas Box in July of that year - it's now available in my free short story collection, Checkmate & Other Stories) it seemed like a good idea to keep using the same name.
You might find that there is already an author with your name. Maybe the domain name you want is unavailable. Perhaps you just fancy a change. But what are the pros and cons to using a pen name?
PositiveKeep your writing and your work life separate
If you're not lucky enough to be a fulltime writer, then there's a good chance you'll want to keep your writing and your job separate. I use my social networking spaces for my writing life, and I certainly don't want my blog to be the first thing that pops up if a potential employer decides to Google me (instead, they get my LinkedIn, which is for my professional life).
It's easier to keep your private life private if you're not using your real name. Obviously there's still something to be said for keeping certain things offline. Don't want strangers seeing photos of your kids? Don't post them in public. People sometimes forget that the Internet is public (unless you know how to work those privacy settings) and once you've posted something, it's very difficult to remove it without many people you don't know already having seen it.
Creating a pseudonym or pen name allows you a certain amount of self re-invention. If you were bullied mercilessly at school but have emerged as a strong and independent person, adopting a pseudonym allows you to distance yourself from the person you were then, under that name, and sell yourself as the person you are now, under your new name. Plus, you can even go so far as to create an entire persona to go with the pseudonym, turning your pen name into a character in its own right. Look at Stephen King - he even collaborated with himself when he did the Stephen King/Richard Bachman books.
Different genre, different name
Anne Rice writes under three different names, depending on the genre. You might decide to do the same - after all, if you write both hardcore science fiction and chick lit, you might want to differentiate between the two so as not to confuse readers, unless you think the readers of the fluffy Bridget Jones-esque books with the pastel covers will love your stories of quantum mechanics gone wrong. In addition, you may not want to embarrass/horrify your family if you write in certain genres, and adopting a pen name for those works allows you to put a certain amount of distance between you and your writing.
It's harder to prove a case of plagiarism if you're not using your real name. Indeed, if your real name is Jane Smith but you write as Madagascar Fairbanks, then how can you prove what's stolen is actually yours, and that you're really Madagascar? Now, I'm at least using my surname and there are photos of me on my blog so proving my identity, and thus my authorship of my work, is easier than if I were to adopt a pseudonym.
Publishing contracts require you to sign under your real name anyway so you might decide that it's just easier to use your real name instead of signing under one name and promoting under another. I've heard stories of authors being horrified to see a magazine print one of their stories under their real name, despite them stressing the pen name should be used.
No stone unturned...
The Internet is a big place and maintaining anonymity can be difficult. So if you're choosing a pen name to remain anonymous, you might find it harder than you thought. It's not impossible, especially if you pay for webspace and ensure you enable the privacy settings, but people will always track down information if they're dedicated enough. A fledgling writer won't have this problem, but it's something to think about if your career takes off.
It's up to you if the pros outweigh the cons, or vice versa, but whatever you do, have fun with it! Writing should be enjoyable. Now excuse me, I'm off to invent another me...