Some reasons for using a pen name:
Conflicting genres:
For example, I write stories for children and books for adults/books with adult themes so it wouldn’t be sensible or appropriate for me to use the same name for both styles. I have a different name for each. Otherwise, what if the child searched for other books by me and found and started reading something for adults? Or an adult was equally confused and thought I was talking down to them? The last thing I want is to confuse or harm my readers! Although I do make sure it’s pretty obvious with the cover design and the book blurb, you never know if people actually look that closely!
Writing as your business:
You might want to keep your writing and personal life separate. Perhaps you write in a genre or on a topic that you don’t want your loved ones, or the boss from your day job, to find out about. You might work for a school but write erotica which could cause a conflict of interest. An extreme example is John Le Carre, who’s real name is David Cornwell, for instance, and is forbidden to write under his own name as he was previously involved with the British Secret Service.
Ease of name:
If you have a particularly long name you might find it doesn’t fit nicely on the cover. This wouldn’t look very good on a thumbnail image when your readers are searching for you. In that case you could consider using initials for your first name(s) or shortening any hyphened surnames.
If you have an unusual name that people might find difficult to spell, it might be best to simplify it so people can find you in searches. And if you become really famous for your writing you'll want people to pronounce your name correctly too when they introduce you on the TV or radio!
Suiting the genre:
Some authors change their name to suit a particular genre. Lemony Snicket for example sounds far more fun and kid’s author than his real name, Daniel Handler. (and the unusual-ness of it has probably helped too!). You could go for something edgy if you write thrillers or feminine for romance if you are a male author. Some female authors still will write under a male name as it tends to work better for some audiences. To be gender neutral you could also opt for the initials again.
Collaboration:
If you are working with another author or two and would rather merge the names than have multiple authors on the cover, this would work too. It can also help if you can’t decide who’s name should come first!
Confidence:
Some people feel more confident writing under a different persona. I did when I first started out. I didn’t want people to know it was me and yet still wanted to be known as a writer! Go figure! It gives you freedom to experiment in your writing and see where your skills are. Later when you are more confident in your style etc then you can branch out either with your own name or another pen name.
Honour a loved one:
If someone has greatly influenced your life and your writing, and you feel the best way to honour them is by using all or part of their name as your pen name, then that could be another option. If the person is alive it would be best to check that its ok with them though especially if you intend to write anything that could be controversial. If the person is not still around then it would be worth checking with their closest relatives so you don’t upset them.
To be different:
Some names are very common. It can happen sometimes that you have the same name as someone who already has books on the shelves or bestseller lists. No matter how great your real name is, to save any confusion you would be best to change yours. Don’t even think about trying to piggyback off the already famous author’s success, they’d soon sue you for trying! In any case why would you want to be the next [insert famous author’s name] when you can be the first you?
When you’ve chosen a name, sit tight on it for a while and then see if you still like it a week or so later. You might decide not to go with your first thought or realise it sounds too cliché or actually it doesn’t look good on a cover or it’s hard to use as an autograph.
If you use it straight away and then change your mind it can be hard to alter, especially if you’ve already published, for example, on Amazon. It’s a pain to have to change your files, covers, reuploading from scratch (as you can’t just change the author name on Kindle Direct) and if you’re on Author Central you’d have to contact Amazon and give a good reason why you want to change your name. Otherwise they could just refuse to. Which won’t look good when people are trying to find other books by whatever name they know you by.
With your pen name you’re building a brand so it’s important to get it right from the start. Whenever you’re at a speaking event or book signing, or if you respond to emails from readers remember to sign off with your pen name to help avoid confusion and to remain consistent.
If you have more than one pen name you’ll need to consider how you’ll manage the multiple websites or social media accounts you’ll need for each one. Think about why you want to keep things separate from your real life and if its possible to merge similar genres for example romance and erotica or thriller and mystery to make things easier.
One final thing to consider is if you’re working with an agent or publisher you will want them to know your real name for any contracts you have to sign and any finance documents (eg for tax purposes), but you can add a line that says something like ‘writing as [pen name]’ to be more transparent.