Some groups of people are "often excluded from wider health services" affecting their end-of-life care, a report found.
Groups mentioned in the report as being disadvantaged are people who are black or from another ethnic minority, the homeless, travellers or the vulnerable, frail and dementia sufferers.
The findings are from a national review by the Care Quality Commission (CQC), England's independent health and social care regulator.
People who are lesbian, gay, bisexual, and transgender (LGBT) felt their partners were often not involved in their care in the same way that a heterosexual partner would be, the CQC said.
The report also said: "The needs of people from some groups, including people with a mental health condition, people with a learning disability, people who are homeless, and gypsies and travellers, are not always considered by services and commissioners.
"People from these groups are often also excluded from wider health services, which is a significant barrier to receiving good care at the end of life."
An "organisational lack of familiarity" with different cultural preferences, poor communication and not identifying someone's needs early enough were named among the problems.
It is suggested that many people, except those who had been diagnosed with cancer, are overlooked in a system that is designed around the needs of others.
A lack of awareness of the number of homeless people locally adds to the problem.
The CQC said a third of clinical commissioning groups (CCGs), the NHS firms which organise the delivery of NHS services in England, have not looked at how they will care for people who are at the end of their lives.
It found that only 67% of the 40 CCGs it surveyed said they had assessed the end-of-life care needs of their local populations - meaning that one in three had not.
The review also noted that while over 90% of the hospices it had inspected were rated by CQC as good or outstanding, 42% of end-of-life care services in acute hospitals were inadequate or needed improvement.
The review states: "Under the Equality Act 2010, commissioners and providers have a legal duty to consider the needs of individuals in their day-today work.
"We found that not all commissioners and providers are fulfilling this duty in relation to the delivery of end-of-life care."
It was found: "Some people are not being identified early enough, while poor communication is preventing others from receiving good end of life care. The needs of people from different equality groups and people who may be vulnerable because of their circumstances are not always considered.
"This means that people may not receive end of life care that responds to their needs and preferences."
Some sufferers told the CQC they felt they "were not always able to access the right care at the right time, particularly if they had conditions other than cancer".
Heartrending testimony from a widow included memories of how her dying husband's needs were ignored simply because he was a naturally quiet man "who accepted what was going on because he had no choice".
The review calls for a shift away from focusing on only identifying people who are clearly in the last year of life, and towards having conversations about wishes and preferences for care in the last phase of life at an earlier stage.
The CQC wants leaders of local health and care systems, commissioners and providers, hospices and GPs to help in creating widespread good quality personalised end-of-life care.
Work has already started to try and tackle the discrimination levels but " there is still much more to do," according to Hospice UK chief executive Tracey Bleakley and Professor Bee Wee, of NHS England.
Marie Curie chief executive Dr Jane Collins said: "It (the report) also shows unequivocally that a third of local NHS clinical commissioning groups (CCGs) are not assessing end-of-life care needs in their area and must up their game. Without assessing the needs of all local people, high quality care of the dying for all will remain an ambition. It must become the norm."
Simon Chapman, of the National Council for Palliative Care, said: "It is unacceptable for anyone to receive poor quality end of life care. It is especially troubling that people in these groups, so often overlooked and marginalised by the rest of society, also suffer poor care at the end of their lives."
Phil McCarvill, of the NHS Confederation, said: "It is essential that we learn from this report."