Ed Miliband has criticised media personalities Jeremy Clarkson and Janet Street-Porter for belittling people with mental illness and contributing towards the stigma that sufferers feel.
The Labour leader said the taboo around mental health was "one of the most serious challenges" facing the country, affecting one in four people directly and costing the economy billions of pounds a year.
He praised the example of people like cricketer Marcus Trescothick and television presenter Stephen Fry for speaking out about their battles with depression.
But he said "far too often" there was "scepticism and abuse" that reinforced the taboo about mental health meaning many people who struggle with it do not feel able to discuss it or seek help.
"It's not just casual name calling in the streets or the school playground. There are still people who abuse the privilege of their celebrity to insult, demean and belittle others," he said in a speech at the Royal College of Psychiatrists.
"Such as when Janet Street-Porter in a shocking article says that depression is 'the latest must-have accessory' promoted by the 'misery movement'. And Jeremy Clarkson, who may have at least acknowledged the tragedy of people who end their own lives, goes on to call them 'Johnny Suicides' whose bodies should be left on train tracks rather than delay journeys.
"It is attitudes like these that reinforce the stigma that blights millions of people's lives, and holds our country back. The fight against racism, against sexism and against homophobia, made the acceptable unacceptable. So we should join the fight against this intolerance. It is wrong, it costs Britain dear, and it has to change."
Mr Miliband announced the creation of a taskforce headed by the chair of Barts NHS Trust, Stephen O'Brien, to draw up a strategic plan for mental health in society. He called for the NHS constitution to be re-written to give patients the same legal right to therapies for treating mental illness as they already have to drugs and treatments for physical illness.
Labour would also ensure that training for all professional staff covers mental health and would integrate physical and mental healthcare more effectively, he said.
In his first major speech since he claimed the One Nation mantle of Benjamin Disraeli for Labour, Mr Miliband argued that Britain could not be one nation if it wrote off people with mental illness.