Guy Friday (Man Friday)

Entry in progress—B.P.

Wikipedia: Friday (fictional character)
Friday is one of the main characters of Daniel Defoe’s 1719 novel Robinson Crusoe. Robinson Crusoe names the man, with whom he cannot at first communicate, Friday because they first meet on that day. The character is the source of the expression “Man Friday”, used to describe a male personal assistant or servant, especially one who is particularly competent or loyal. Current usage also includes “Girl Friday”.
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Idiom
The term Man Friday has become an idiom, still in mainstream usage[citation needed], to describe an especially faithful servant or one’s best servant or right-hand man. The female equivalent is Girl Friday. The title of the movie His Girl Friday alludes to it and may have popularised it.

(Oxford English Dictionary)
man Friday, n.
Someone regarded as having the characteristics of Defoe’s man Friday; a servant, an attendant; a personal assistant who does all kinds of work; a companion.
a1809 R. M. Wilson Jrnl. (modernized text) in H. G. Thursfield Five Naval Jrnls. (1951) 247 The steward..puts great confidence in his Man Friday.
1823 W. T. Moncrieff Cataract of Ganges! i. ii. 9 Couldn’t I be a Man Friday to wait upon you?
1869 ‘M. Twain’ Innocents Abroad xiii. 119 We asked our man Friday’s name.
1884 G. W. Cable Dr. Sevier xlvi. 341 With a presidential candidate on one side and his vice-presidential man Friday on the other.
1887 Athenæum 16 Apr. 504/3 Count von Rechberg,..was Prince Bismarck’s man Friday.

OCLC WorldCat record
Departments - NEWS YOU CAN USE - My Girl (and Guy) Friday - Temp workers get a morale and motivation boost by showing their other talents on a music CD—Plus How To, Reality Check, Trend Watch, News Flash, Top Ten, and Training Alert. That’ s a lot of news you can use!
Publisher: Alexandria, VA : American Society for Training and Development, c1991-2001.
Edition/Format: Article Article : English
Publication: Training & development. 53, no. 2, (1999): 10
Database: ArticleFirst