Is euthanasia ethical?

According to BBC News, these terms surrounding the issue of euthanasia, although they are not always used consistently from country to country.

• Euthanasia is an intervention undertaken with the intention of ending a life to relieve suffering, for example a lethal injection administered by a doctor (Note: for something truly disgusting, check out the Liverpool Care Pathway - now there's a lovely title if there ever was one - the LCP basically means that the patient (usually a elderly person) is sedated then denied food and water until they die of starvation and dehydration)
• Assisted suicide is any act that intentionally helps another person kill themselves, for example by providing them with the means to do so, most commonly by prescribing a lethal medication
• Assisted dying is usually used in the US and the UK to mean assisted suicide for the terminally ill only, as for example in the Assisted Dying Bills recently debated in the UK