It occurs to me that a butler is a figure who only seems to appear in references to Britain. Yet other European countries with all their grand houses, chateaus, and castles must have equivalent positions. What are they called?
Looking at the definintion of butler, I’d say it would be butiller, or bouteiller or the like.
And I find from looking in my dictionary that the English word comes from Anglo-Norman French, so it’s not surprising that there’s still a similar word in Modern French.
I would use the word “majordome”.
Dictionary.com doesn’t list that spelling, but suggests majordomo instead.
What would be the difference?
The difference is that “majordomo” is English and “majordome” is French.
Another word you can use would be “valet”. For example, if I was writing a book with a character like Jeeves from the Wodehouse stories, I think the word “valet” would be appropriate. A “majrodome” would be more like someone in charge of a large staff of servants.
I’m a native speaker and I’ve never heard either term. Looking them up, I see that they were used to refer to the crown officer in charge of wine, which makes sense, as bouteille = bottle.
“Majordome” is close to butler, but since it is a cognate of “majordomo”, I’d suggest “valet” as the better translation. Historically, it’s a word that has carried a different meaning but in modern usage a valet is a butler.
There is also the word “domestique”, which is also a very good translation. In Tintin, the archetypical butler, Nestor, is a “domestique”. However, “domestique” is also used to refer to house servants in general, whereas butler is, I think, a more specific position.
Addendum: Wodehouse’s My Man Jeeves was translated in French as Mon valet de chambre. So, in this case, it’s valet de chambre, or simply valet.
In the English tradition, a valet is not at all the same thing as a butler. A valet is a personal servant. A butler runs the household. Butler as a word and position probably got corrupted by Hollywood movie versions of butlers, which scanted the butler’s chores.
What about in other countries, Germany, Italy, Spain? There must be similar positions.
In Spain the butler is mayordomo; the valet (Jeeves) is criado or criado personal. Criado personal would only be used to differentiate a valet from the rest of the service in a household with many male servants. Criado also means (male) servant.
Doncella would be a lady’s personal maiden; criada is (female) servant; chacha is cleaning lady and not used anymore; señora de la limpieza, limpiadora is cleaning lady and in use (and now we get señores de la limpieza too, cleaning men).
The words criado/a lit. mean raised, as they often “entered service” very young and were raised by the family they were serving. One of the cleaning ladies Mom had started working for her at 14 - Mom taught her to clean, cook, and so forth.
I was speaking from a historic sense of the origin of the word. Those were the duties of the first butler, obviously their duties expanded in time, but the name denoting their first duties was kept and a form of it is used today: butler. 
Pierre?
Judging by the Wodehouse novels, which I think were intended to be reasonably accurate as to the settings, the butler indeed was the head of the staff and responsible for the whole operation of running the house. A valet was a personal servant. Footmen were other general household staff not designated to assist a particular member of the household. Anthony Hopkins’ character in Remains of the Day was a butler.
Oddly, in Wodehouse there seems to be no occurrence of the head housekeeper, who seems to have been the highest ranking female staff member.