“It may be better to be a live jackal than a dead lion, but it is better still to be a live lion. And usually easier.”

Quoted in [Moss, Stephen, Captain Scott centenary: Storm rages around polar explorer's reputation, The Guardian, 28 March 2012, http://www.theguardian.com/uk/2012/mar/28/captain-scott-antarctic-centenary-profile]

Più tosto can vivo che leone morto.
Della Morte, p. 525.
Translation reported in Harbottle's Dictionary of quotations French and Italian (1904), p. 394.

Walden (1854)
Context: A living dog is better than a dead lion. Shall a man go and hang himself because he belongs to the race of pygmies, and not be the biggest pygmy that he can? Let every one mind his own business, and endeavor to be what he was made. Why should we be in such desperate haste to succeed, and in such desperate enterprises? If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away.<!--pp.366-367

Attributed in "Duce (1922-42)" in TIME magazine (2 August 1943)
Also quoted by Generale Armando Diaz in "Il pensiero dei leoni" in Il Carroccio. The Italian review (1922) attributed to graffiti by an unknown soldier https://archive.org/stream/ilcarroccioitali15newyuoft#page/14/mode/2up
Though not precisely a repetition of any of them, this is somewhat resembles far earlier remarks attributed to others:
An army of sheep led by a lion is better than an army of lions led by a sheep.
Attributed to Alexander the Great, in The British Battle Fleet : Its Inception and Growth Throughout the Centuries to the Present Day (1915) by Frederick Thomas Jane
To live like a lion for a day is far better than to live like a jackal for a hundred years.
Tipu Sultan, as quoted in Encyclopedia of Asian History (1988) Vol. 4, p. 104
It is far better to live like a tiger for a day than to live like a jackal for a hundred years.
Tipu Sultan, as quoted in Tipu Sultan : A Study in Diplomacy and Confrontation (1982) by B. Sheikh Ali, p. 329
I should prefer an army of stags led by a lion, to an army of lions led by a stag.
Chabrias, as quoted in A Treatise on the Defence of Fortified Places (1814) by Lazare Carnot, p. 50
He has been frequently heard to say, that in this world he would rather live two days like a tiger, than two hundred years like a sheep.
Tipu Sultan, as quoted in A View of the Origin and Conduct of the War with Tippoo Sultaun; Comprising a Narrative of the Operations of the Army under the Command of Lieutenant-General George Harris, and of the Siege of Seringapatam (London, G. and W. Nicol, 1800) by Alexander Beatson, pp. 153-154. http://oudl.osmania.ac.in/bitstream/handle/OUDL/7905/212261_Origin_And_Conduct_Of_The_War_With_Tipoo_Sultaun.pdf https://indianhistorybooks3.files.wordpress.com/2014/06/99999990039373-view-of-the-origin-and-conduct-of-the-war-with-tipoo-sultan.pdf
1940s

Out of Step (1985)

1850s, The House Divided speech (1858)
Context: There are those who denounce us openly to their own friends and yet whisper us softly, that Senator Douglas is the aptest instrument there is with which to effect that object. They wish us to infer all this from the fact that he now has a little quarrel with the present head of the dynasty; and that he has regularly voted with us on a single point upon which he and we have never differed. They remind us that he is a great man, and that the largest of us are very small ones. Let this be granted. But "a living dog is better than a dead lion." Judge Douglas, if not a dead lion, for this work, is at least a caged and toothless one. How can he oppose the advances of slavery? He does not care anything about it. His avowed mission is impressing the "public heart" to care nothing about it. A leading Douglas Democratic newspaper thinks Douglas's superior talent will be needed to resist the revival of the African slave-trade. Does Douglas believe an effort to revive that trade is approaching? He has not said so. Does he really think so? But if it is, how can he resist it? For years he has labored to prove it a sacred right of white men to take negro slaves into the new Territories. Can he possibly show that it is less a sacred right to buy them where they can be bought cheapest? And unquestionably they can be bought cheaper in Africa than in Virginia. He has done all in his power to reduce the whole question of slavery to one of a mere right of property; and as such, how can he oppose the foreign slave trade — how can he refuse that trade in that "property" shall be "perfectly free" — unless he does it as a protection to the home production? And as the home producers will probably not ask the protection, he will be wholly without a ground of opposition.

Attributed to Napoleon in Napoleon (1941) by Yevgeny Tarle, this is a variant of an ancient proverb often attributed to many military and political figures, including Alexander the Great, and the even earlier figure Chabrias (Χαβρίας).
Misattributed

Attributed to Alexander, as quoted in The British Battle Fleet: Its Inception and Growth Throughout the Centuries to the Present Day (1915) by Frederick Thomas Jane, but many variants of similar statements exist which have been attributed to others, though in research done for Wikiquote definite citations of original documents have not yet been found for any of them:
I should prefer an army of stags led by a lion, to an army of lions led by a stag.
Attributed to Chabrias, who died around the time Alexander was born, thus his is the earliest life to whom such assertions have been attributed; as quoted in A Treatise on the Defence of Fortified Places (1814) by Lazare Carnot, p. 50
An army of stags led by a lion would be better than an army of lions led by a stag.
Attributed to Chabrias, A History of Ireland (1857) by Thomas Mooney, p. 760
An army of stags led by a lion is superior to an army of lions led by a stag.
Attributed to Chabrias, The New American Cyclopaedia : A Popular Dictionary of General Knowledge (1863), Vol. 4, p. 670
An army of sheep led by a lion are more to be feared than an army of lions led by a sheep.
Attributed to Chabrias, The Older We Get, The Better We Were, Marine Corps Sea Stories (2004) by Vince Crawley, p. 67
It is better to have sheep led by a lion than lions led by a sheep.
Attributed to Polybius in Between Spenser and Swift: English Writing in Seventeenth Century Ireland (2005) by Deana Rankin, p. 124, citing A Contemporary History of Affairs in Ireland, from 1641 to 1652 (1880) by John Thomas Gilbert Vol. I, i, p. 153 - 157; but conceivably this might be reference to Polybius the historian quoting either Alexander or Chabrias.
An army composed of sheep but led by a lion is more powerful than an army of lions led by a sheep.
"Proverb" quoted by Agostino Nifo in De Regnandi Peritia (1523) as cited in Machiavelli - The First Century: Studies in Enthusiasm, Hostility, and Irrelevance (2005) by Mathew Thomson, p. 55
Greater is an army of sheep led by a lion, than an army of lions led by a sheep.
Attributed to Daniel Defoe (c. 1659 - 1731)
I am more afraid of one hundred sheep led by a lion than one hundred lions led by a sheep.
Attributed to Charles Maurice de Talleyrand-Périgord (1754 – 1838) Variants: I am more afraid of an army of 100 sheep led by a lion than an army of 100 lions led by a sheep.
I am not afraid of an army of one hundred lions led by a sheep. I am afraid of army of 100 sheeps led by a lion.
Variants quoted as an anonymous proverb:
Better a herd of sheep led by a lion than a herd of lions led by a sheep.
A flock of sheep led by a lion was more powerful than a flock of lions led by a sheep.
An army of sheep led by a lion would defeat an army of lions led by a sheep.
It were better to have an army of sheep led by a lion than an army of lions led by a sheep.
An army of sheep led by a lion, will defeat an army of lions led by a sheep.
An army of sheep led by a lion would be superior to an army of lions led by a sheep.
Unsourced attribution to Alexander: I would not fear a pack of lions led by a sheep, but I would always fear a flock of sheep led by a lion.
As one lion overcomes many people and as one wolf scatters many sheep, so likewise will I, with one word, destroy the peoples who have come against me.
This slightly similar statement is the only quote relating to lions in The History of Alexander the Great, Being the Syriac Version of the Pseudo-Callisthenes (1889) as translated by E. A. Wallis Budge, but it is attributed to Nectanebus (Nectanebo II).
Disputed

The Life and Adventures of http://books.google.com/books?id=IZ9CAAAAYAAJ&q=%22better+to+have+a+Lyon+at+the+Head%22+%22an+Army+of+Sheep+than+a+Sheep+at+the+Head%22+%22an+Army+of+Lyons%22&pg=PA33#v=onepage Mrs. Christian Davies (1741)