Mark Thompson is the big beast of the BBC, in stature, in intellect and in rhino-hide toughness. And, as his decision over screening the Gaza charity appeal has shown, he seems to possess unshakeable confidence in his own judgement.
Unlike his predecessor, Greg Dyke, Thompson, 51, has never aspired to be popular at all costs, or to make people feel good. He is a leader and a loner. So his flinty refusal to allow the appeal for a blitzed Gaza on to the BBC airwaves is part of what makes him tick. It publicly highlights his willingness to strike out on a lonely path, in defence of what he believes intellectually is right: specifically, protecting the BBC's duty of impartiality across all services.
It might seem patronising, as John Humphrys observed to him, during a tense Today interview, that ordinary people are deemed unable to separate a humanitarian plea for charity from the task of reporting a bitter conflict. But the key to Thompson is his powerful focus on the long-term future of the BBC, which he joined after the Jesuit Lancashire boarding school, Stonyhurst and Merton College, Oxford.
He is an admirer of strong institutions and relishes family life in moneyed north Oxford, where he cooks, cycles and practises his Catholic faith. The son of a widowed mother, he is an interesting mix. The consensus of those who know him is that, while he seems approachable, the closer you get to him, the colder he seems. He is unlikely to have lost any sleep over the Disasters Emergency Committee decision.
As soon as he joined the BBC in 1979 as a production trainee, the able Thompson was destined for the top. Crucially, at the age of 29, he was selected as one of John Birt's young lions, relaunching the (then) Nine O'Clock News with analysis, to his boss's satisfaction.
His posts have included output editor on Newsnight, editor of Panorama and head of factual programmes; for BBC2 he backed an ambitious young chef called Jamie Oliver before heading national and regional broadcasting, an unglamorous stepping stone to running BBC television.
He would be a corporation lifer except for a stint between 2002 and 2004 when he became chief executive of Channel 4. There he adopted loud-checked shirts and stubble, forced through cuts and criticised the channel's creative record. He explored, clumsily, a solution to its woes by pursuing a merger with Five. The exile ended when Dyke resigned from the BBC following Lord Hutton's report in January 2004. Dyke told Thompson he had to come back to save the BBC. Its new chairman, Michael Grade, agreed.
So since May 2004 he has thrown himself into the defence of the licence fee and its reformed role as the cornerstone of British broadcasting. He has been ruthless in doing this, accepting that part of the licence fee was ring-fenced to pay for the digital TV switch-over.
Thousands of staff were axed, to help accommodate independent producers, or relocated to Salford and beyond, a deeply political move to re-engineer a BBC so rooted in British life that it cannot be cut out.
He is no shrinking violet in handing out advice: critics call it arrogance. Recent interventions in the debate about public service broadcasting have seen him resurrect the belief that Channel 4 and Five might usefully merge - while devising an alternative policy of partnerships, to help out. One such canny offer, to enable ITV to continue to make regional news, has won over MPs.
But he has weak points. Stephen Carter, the broadcasting minister, noted (when he was head of Ofcom) that Thompson was not very commercial during his tenure at Channel 4.
But his seriousness, his ability to think fast and debate deep is unmatched at the top of the BBC.
Many institutional weaknesses have been exposed in his regime, from phone-line scandals and fakery to the Jonathan Ross and Russell Brand affair.
Thompson was with his family - his American wife, Jane Blumberg and their three children - in Sicily when "Sachsgate" broke. He had left no clear chain of command with his deputy.
Nor has the management in radio performed well. Editorial guidelines are being overhauled.
Two of the outstanding issues are grossly overpaid stars and inflated executive packages including his own, which totalled £816,000 last year - though he has refused bonuses.
But as for a successor - there is no obvious candidate or any challenger stamping his or her feet, ready to exploit his unpopularity.
Broadcasting is short of first-class leaders. Perhaps his only credible successor is Helen Boaden, director of BBC News. She, wisely, has adopted a low profile.
But, then, being director general of the BBC is a near impossible job, running intensely scrutinised services, many live, 24 hours a day, ever-dependent on judgements and decisions taken by thousands of stressed people.
During Thompson's period at the BBC he has seen Alasdair Milne sacked (1987), Sir Michael Checkland provoked into resigning (1992), John Birt stamp his revolution and Greg Dyke deposed. As he headed up another initiative this week, this time on the arts, a lesser man might have mused that being director-general is a job never done, and one likely to end in tears.
Thompson will be at the BBC until his chairman and the trustees have had enough. There is no sign, so far, of that yet.