In thermodynamics, engine pioneers refers to innovators in the area of the development of engines, enabled by heat, combustion, or vacuum creation (e.g. vacuum pump, attached to vacuum bulb, attached to piston and cylinder), able to lift a weight though unit height and or turn a crank arm so to do work.

Overview
The following is a work-in-progress chronological listing of engineers behind vacuum engines, generally, e.g. gunpowder engine, or heat engines, e.g. steam engines, air engines, etc., specifically, and or theoretical engines, e.g. Carnot engine, in overall design; the code EP:#, e.g. Hero (EP:3), is shorthand notation for that person's engine pioneer ranking:

		Person	Date	Engine	Type	Description
		--------------------------------------------------------------------------		-------------------------------------------------------
1.	— 39	Archimedes (287-212BC)	c.235BC	Architronito (steam cannon)		Invented, according to da Vinci (c.1500), a so-called architronito, or steam-powered cannon that throws 70lb iron balls, via the action of “great noise and fury”, at the enemy, by the action of heat derived from burning coals; diagrams of which are found in da Vinci’s notebooks.
2.	— 73	Ctesibius (c.285-222BC)	c.230BC	Aeolipile
3.	— 63	Hero (c.10-70AD)	c.50AD	Aeolipile
4.	— 7	Leonardo da Vinci (1452-1519)	1508	Da Vinci engine [s]	Gunpowder engine Steam cannon Steam turbine	Da Vinci, according to the arguments of Ladislao Reti (1969), was the first to: state that condensed steam makes a vacuum, before Gerolamo Cardano (1550) is blurrily-cited to have done so; first to make a gunpowder engine, before Christiaan Huygens (1673), Denis Papin (1674), and Jean Hautefeuille (1678); was the “unknown author” cited by Giovanni Branca (1629), in respect to his Hero-like steam turbine; and that he was the true inventor of the steam-powered cannon (Architronito), not Archimedes, per argument that Archimedes only invented an ordinary gunpowder cannon.
5.	— 297	Gerolamo Cardano (1501-1576)	1550
5.		Lazarus Ercker (c.1530-c.1594)	1574
6.		Giovanni Porta (1535-1615)	c.1601	Porta engine (improved Hero fountain)		In his Spiritali, following or amid a French translation of Hero’s steam machine work, reproduced Hero's aeolipile and his solar boiler device, after which, he added an illustrated modified variant of his own, similar to a combination of the above two devices; as shown below, wherein, a fire is put under flask a, filled with water, which makes steam, that enters closed container b, filled with cold water, which forces the water to shoot out of tube c, into the external air.
7.	— 410	Cornelis Drebbel (1572-1634)	1609
8.		Salomon de Caus (1576-1626)	1615	Caus engine
9.		Giovanni Branca (1571-1645)	1629		Steam turbine (modified aeolipile)
10.		David Ramsay (c.1590-1653)	1630	Ramsay engine (aka fire engine)		Under the idea influence of de Caus, applied for a patent for a device “To Raise Water from Lowe Pitts by Fire”; supposedly, however, there is no information concerning what he had in mind or what he did with it.
11.	— 11	Galileo Galilei (1564-1642)	1632	Galileo engine (vacuum measuring device)
12.	— 37	Otto Guericke (1602-1686)	c.1647	Guericke engine (aka vacuum pump)	Vacuum engine
13.		John Wilkins (1614-1672)	1648			His Mathematical Magic (1648) presented a chapter on the history of heat engines of various sorts, e.g. aeolipile, Giovanni Branca’s device (1629), and Cardano's smoke jack, and Cornelis Drebbel’s sun-powered clavichord (1609).
14.		Edward Somerset (1603-1667)	1654	Worcester engine (Thurston, 1878) (aka Somerset engine)		Penned his Century of Inventions (1654), not published till 1663, which gave a summary of the Hero-like devices built in the last century, including one made by him, that raised water up the side of his castle by fire.
15.	— 18	Robert Hooke (1635-1703) \| #1	1658	Pneumatical engine (aka machine Boyleana)		An improved re-construction of the Guericke engine, built per order of Robert Boyle.
16.		Samuel Morland (1625-1695) \| #1	1661			Was granted a ‘monopoly’, according to a warrant of Charles II, for an engine for raising water out of mines by means of ‘air and powder conjointly’.”
17.	— 415	Ferdinand Verbiest (1623-1688)	c.1670	Verbiest auto-mobile
18.	— 33	Christiaan Huygens (1629-1695)	1673	Huygens engine	Gunpowder engine; Piston and cylinder
19.	— 18	Robert Hooke (1635-1703) \| #2	1675	Hooke engine	Theoretical
20.	— 185	Denis Papin (1647-1712) \| #1	1674			A few years subsequent to Boyle's discoveries [1662], Papin was installed in the laboratory at the Parts Academy of Sciences, and under the directions of Christiaan Huygens, was employed in experiments with the pneumatic engine, after the model of Boyle and Hooke’s, and the examination of the force of gunpowder, and also of the force of water rarefied by fire. An account of these experiments was published in 1674, and in the following year Papin left Paris, and proceeded to London. [2]
21.		Jean Hautefeuille (1647-1724)	1678	Hautefeuille engine	Gunpowder engine
22.	— 185	Denis Papin (1647-1712) \| #2	1679	Papin digester		invented what he called a "digester or engine for softning bones", aka "bone digester", or Papin's digester as it later came to be called
23.		Samuel Morland (1625-1695) \| #2	1683	Morland engine		Submitted a project to Louis XIV for raising water by means of steam, accompanying it with ingenious calculations and tables.
		Denis Papin (1647-1712) \| #3	1688	Papin engine (gunpowder)
24.	— 185	Denis Papin (1647-1712) \| #3	1690	Papin engine (steam)	Theoretical; Piston and cylinder
25.	— 332	Thomas Savery (c.1650-1715)	1698	Savery engine (aka Miner’s friend)	Working
26.		Thomas Newcomen (1664-1729)	1705	Newcomen engine (improved Savery engine)
26.		Henry Beighton (1687-1743)	1717			In two entries of the Royal Society (1717), he made an improved Newcomen engine (Ѻ); sometime thereafter he began to associate with John Desaguliers. (Ѻ)
27.		John Desaguliers (1683-1744)	1718
28.	— 218	James Watt (1736-1819)	1765	Watt engine (improved Newcomen engine)		Made a number of inventions and design improvements to the functionality of the steam engine, including: separate condenser (1765), the fly-ball governor (1788), and the definition of "pony power" (or horse power).
29.		Joshua Rigley (c.1710-1785)	c.1768
30.		John Smeaton (1724-1792)	1769	Smeaton engine (improved Newcomen engine)
31.		Nicolas Cugnot (1725-1804)	1769	Cugnot auto-mobile
32.		James Pickard (c.1735-1800)	1780	Pickard engine
33.		Jonathan Hornblower (1753-1815)	1781	Hornblower engine (compound engine)
34.		Arthur Woolf (1766-1837)	1803			Designed an improved boiler for producing high pressure steam (1803) and invented a compound steam engine (1804) generally using the expired patent of Hornblower.
35.	— 499	Richard Trevithick (1771-1833)	1804	Trevithick locomotive
36.		George Stephenson (1781-1848)	1814
37.	— 25	Sadi Carnot (1796-1832)	1824	Carnot engine	Abstract

(add)

Quotes
The following are related quotes:

“When a comparison is made between Savery’s engine [1698] and those of his predecessors, the result will be in every respect favorable to his character as an inventor, and as a practical engineer; all the details of his invention are made out in a masterly style, and accidents and contingencies are provided for, so as to render it a real working engine; whereas De Caus [Caus engine, 1615], the Marquis of Worcester [Worcester engine, 1663], Sir Samuel Morland [Morland engine, 1683], and Papin [Papin engine, 1690], though ingenious philosophers, only produced mere outlines, which required great labor and skill of subsequent inventors to fill up, and make them sufficiently complete to be put in execution.”
— John Farey (1827), Treatise on the Steam Engine; cited by Dionysius Larder (1840) in The Steam Engine (pg. 58) [1]

“James Watt is rightly enough described as the ‘father of the modern steam engine’. The story of his life has been so frequently told that no one would have thanked Galloway for repeating it; he has accordingly preferred to trace the history of the modern prime-mover from the time when modern philosophy rendered it possible for the genius of Papin, Savery, Newcomen, and, lastly, Watt, to turn to account the facts discovered in the laboratory. The aeolipile of Hero, who flourished about 150 BC, may have been, in the estimation of some rather imaginative minds, the precursor of the steam-engine, just as the projects of De Caus, Branca, Ramsey, and the Marquis of Worcester were steps in the evolution of the genus steam-engine, but between Hero and Watt there are a great many missing links. It is rather in the scientific discoveries of the 17th century that we must look for the germ of the steam-engine, and such men as Galileo, Torricelli, Pascal, and Otto von Guericke take a place in the list.”
— Anon (1881), “The History of the Steam Engine: Overview of Galloway’s The Steam Engine and its Inventors” [2]

See also
● Engine development timeline
● Timeline of thermodynamics

References
1. (a) Farey, John. (1827). A Treatise on the Steam Engine: Historical, Practical, and Descriptive. Longman.
(b) Lardner, Dionysius. (1840). The Steam Engine: Explained and Illustrated – With an Account of its Invention and Progressive Improvement and its Application to Navigation and Railways; also Including a Memoir of Watt. Taylor and Walton.
2. (a) Galloway, Elijah. (1826). History of the Steam Engine: From its First Invention to the Present Time. Cowie.
(b) Anon. (1881). “The History of the Steam Engine: Overview of Galloway’s The Steam Engine and its Inventors” (Ѻ), English Mechanics and the World of Science, 32:507-08, Feb 4.