Naturalist and entomologist George Masters was born in England and migrated to Australia around 1856.  On the 2nd June 1864, he was appointed assistant curator and collector to the Australian Museum in Sydney.  In an article entitled "The Australian Museum" printed in the Maitland Mercury & Hunter River General Advertiser of the 6th June 1867 (p. 4), Masters's acquisition of Tasmanian specimens for the museum (including those of the thylacine), is duly noted:
 

"Mr. George Masters, assistant curator of the Australian Museum, has returned from Tasmania, where he was collecting at that island on behalf of the trustees for the last six months, and has secured a large number of valuable specimens, which would be well worth the inspection of those interested in natural history.  With the exception of two or three species, Mr. Masters has brought all the mammals peculiar to the island, including four "tigers" (Thylacinus cynocephalus), ten "devils" (Sarcophilus ursinus), and many others of the rare animals peculiar to Van Diemen's Land".

. . Portrait of George Masters, by the Crown Studios, Sydney, 1890-1912. Source: Muse Magazine. .

Within the fifth revision of the ITSD (2013), 18 of the Australian Museum's 56 line entries for thylacine specimens are noted as being collected by Masters.

William Frederick Petterd 1849-1910:
 

William Frederick Petterd was a Tasmanian scientist noted for his contributions to the natural history of Tasmania as a conchologist, entomologist, and particularly as a mineralogist. In Tasmania, he is regarded as the "father of mineralogy".  Petterd bequeathed his collection of some 2,500 mineral specimens to the Royal Society of Tasmania, who loaned it to the Trustees of the Tasmanian Museum and Botanical Gardens in Hobart.  The Petterd Collection provides the foundation of the present-day knowledge of Tasmanian minerals.  Petterd showed a keen interest and curiosity as a gifted, self-taught amateur of the natural sciences.  One of his earliest works was "A Monograph of the Land Shells of Tasmania", published in 1879.     Several of Petterd's thylacine specimens are now preserved in the collections of the Australian Museum, the Macleay Museum (University of Sydney), the British Museum of Natural History (London), and the Queen Victoria Museum & Art Gallery (Launceston) (Source: ITSD, 5th revision, 2013).

. William Frederick Petterd.

Charles Macaulay Hoy:

    Charles Macaulay Hoy was an American scientist working at the Smithsonian Institute in Washington, DC.  Hoy visited Australia between June 1919 and April 1922 for the purpose of collecting Australian fauna.  On the 26th April 1921, he travelled to the Arthur River area of Tasmania with the renowned Australian naturalist Harry Burrell, and obtained many valuable specimens.  Hoy did not obtain a thylacine on this specific field trip, but he did procure a skin and skeleton (source unknown) prior to returning home to the United States in 1922 (Source: ITSD, 5th revision, 2013).

Geoffrey Watkins Smith (1919 - 1922):
 

Geoffrey Watkins Smith was a Fellow and Tutor of New College, and Lecturer in the Department of Zoology and Comparative Anatomy at Oxford.  From September 1907, to the spring of 1908, he visited Tasmania to study freshwater crustaceans.  During his time in Tasmania he collected a number of specimens, including the skin of a thylacine (Source: ITSD, 5th revision, 2013).  Upon Smith's return to England, he published an account of his travels in "A Naturalist in Tasmania".  In that account, he notes:     "It will not be very long before it (the thylacine) becomes extinct so that I was careful to gain any information I could with regard to its habits".

. Geoffrey Watkins Smith.