Is it possible to be a successful researcher (engineering/science/arts/medicine) without getting a PhD?

Are there good researchers who do not hold the formal PhDs (considered necessary for a career in research)?

It's certainly possible to do good research without a PhD. However, it's very much more difficult to progress in a research career without some form of higher research degree i.e. an Mphil or PhD.

I know that its almost impossible to score a job in academia without a PhD. But what are the chances of getting a job in an organization (commercial or non-profit) conducting research if a person has some quality publications but no PhD?

'I know that its almost impossible to score a job in academia without a PhD'.

Well not entirely the case. My old University recently appointed a new lecturer who had the grand total of a BSc degree, and from that University too. I'm told she was 'well liked' as a student in the Department.

'I'm told she was 'well liked' as a student in the Department.'

What about the unlucky lot like myself (the ones who were not so 'well liked')?

I think it would depend very much on the level of the position you were seeking. As with any job, good references will count for a lot. A publication record for research will also stand you in good stead. I see a lot of industry jobs in my field advertised as requiring, for example, a PhD with 3yrs experience or an MSc with 6yrs experience. A higher degree of some sort will certainly help.

It's to do with the competitive nature of the job market these days, having extra qualifications will get you higher up the ladder quicker. As there are many more graduates than previously it's a way to sort people out. It is pretty much essential if you want to get anywhere in academia but not so necessary outside of it. It certainly helps but as others have mentioned it depends on want you to get out of it as it is research training. And hard work as well especially if you don't know what you hope to gain out of it!

It is still possible to work your way up in a company/organisation/charity and gain experience that way. Sometimes it is only a Masters is needed. Maybe you could have a look on different sites aimed at final yr students/graduates such as www.prospects.ac.uk.

its not uncommon in engineering because years of industrial experience as a practising engineering can be a greater asset than a purely academic career.

If you are a succesful scientist without a PhD, for example a very good technician there's always the posibillity to get a PhD through publication. i.e. You submitt three or four good papers (first author) back to back and an introduction as your PhD thesis.