O'Brien was the husband of Máire Mhac an tSaoi, noted scholar, writer and poet in the Irish language. Mhac an tSaoi is known under various permutations of English/Irish and married/original versions of her name(s). Here is how she describes herself in a chronology attached to her autobiography, The same age as the state (where she writes as Máire Cruise O'Brien).
Máire Cruise O'Brien (nee Máire MacEntee, in Irish (Gaelic) Máire Mhac an tSaoi, under which name she publishes in that language)
Now, in reading the obituaries of Conor Cruise O'Brien, I was interested to see the form "Máire Mac an tSaoi" used, which is not a version given in the LC authority file. (It differs in that it has 'Mac' rather than 'Mhac'.) Checking elsewhere, I notice that this is also the form used in the review of recent Irish history by Roy Foster, Luck & the Irish: a brief history of change 1970-2000. (Incidentally, John Naughton speculates above that Foster may be the author of the Times obituary mentioned above.)
I also notice that WorldCat shows this form of the name for one item, An galar dubhach, but this may be a mistake as it is shown as Máire Mhac an tSaoi in the National Library of Ireland (in which catalog, incidentally, Máire Mhac an tSaoi is the preferred form) and in the British Library (where Máire O'Brien is the preferred form).
Now, I have forgotten, or more likely may never have known, what one might expect here ('Mhac' or 'Mac') or why the masculine 'Mac' is being used (see the Wikipedia article on Irish names for an explanation of this point), and I don't know what choices Máire Mhac an tSaoi may have made about her name. I have made some limited inquiries but have not researched the issue in any depth.
Anyway, all of this is prelude to the point I want to make. LC and national libraries around the world create authorities data. There may be collaborative structures like NACO to support this.
These types of service seem remarkably well-suited to social approaches. Once I came across several examples of 'Mac an tSaoi' and discovered that it was not recorded in any authority file, I thought that it would be nice to make that known to LC or the National Library of Ireland or the BL or ... However, I have no way of easily doing that which seems a shame. Authorities work - and think NACO here - is a professional activity, hedged around by rules and procedures; it is after all 'authorities' work. However, it would seem sensible to open it up to suggestion and information.
Incidentally, Worldcat Identities, which is programmatically built on top of authorities and bibliographic data does not handle Máire Mhac an tSaoi very well with entries split across several versions of her name and combining her work with some others. This is a good example of why we are working on approaches to allow readers to suggest splitting or merging of Identities.