Notable : Famous : Founder/ originator

Gustav Killian (2 June 1860 – 24 February 1921) was a German laryngologist and founder of the bronchoscopy.

Bernhard Kayser (6 August 1869, in Bremen – 11 May 1954, in Stuttgart) was a German ophthalmologist.
He studied at Tübingen and Berlin, receiving his doctorate from the University of Berlin in 1893. Afterwards, he worked as an intern in Tübingen and as an assistant physician in Freiburg im Breisgau. He was then employed as a ship's physician by the North German Lloyd Shipping Company and spent 2½ years in Brazil as a general practitioner. He later worked as a physician in Brandenburg and Bremen, during which time, he developed an interest in ophthalmology. In 1903 he became a specialist in ophthalmology and relocated to Stuttgart, where he spent the remainder of his life. For many years he was editor of the essay section of the Klinische Monatsblätter für Augenheilkunde.Kayser-Fleischer rings are named after him and Bruno Fleischer. Kayser described the condition in a 1902 paper titled Über einen Fall von angeborener grünlicher Verfärbung des Cornea.

Eduard Kaufmann (24 March 1860, Bonn – 15 December 1931, Göttingen) was a German physician.
The disease Abderhalden–Kaufmann–Lignac syndrome is named for him.

Johann Carl Kaiserling (3 February 1869 - 20 August 1942) was a German pathologist who was a native of Kassel-Wehlheiden.
He studied medicine in Munich, Kiel and Berlin, earning his medical doctorate in 1893. In 1902, he became privatdozent at the University of Berlin, and from 1912 was a professor of general pathology and pathological anatomy at the University of Königsberg.His name is associated with "Kaiserling's fixative", a means of preserving histologic and pathologic specimens without changing the natural color. This fixative is an aqueous solution of formalin, potassium nitrate and potassium acetate. Kaiserling is also known for his pioneer work in the field of photomicrography.

Friedrich Jolly (24 November 1844 – 4 January 1904) was a German neurologist and psychiatrist who was a native of Heidelberg, and the son of physicist Philipp von Jolly (1809–1884).
He studied medicine at Göttingen under Georg Meissner (1829–1905), and in 1867 received his doctorate at Munich. In 1868 he became an assistant to Bernhard von Gudden (1824–1886) and Hubert von Grashey (1839–1914) at the mental institution in Werneck, and in 1870 was an assistant to Franz von Rinecker (1811–1883) at the Juliusspital in Würzburg.
In 1873 Jolly became director of the psychiatric clinic in Strassburg, where he was named as successor to Richard von Krafft-Ebing (1840–1902). In 1890 he succeeded Karl Friedrich Otto Westphal (1833–1890) as director of the neuropsychiatric clinic at the Berlin Charité.
Jolly is remembered for his pioneer research of myasthenia gravis, including the electrophysiological aspects involving abnormal fatigue associated with the disease which forms the basis of Jolly's test. He is credited with coining the term myasthenia gravis pseudoparalytica for the disorder.
He was the author of an influential treatise on hypochondria that was published in Hugo Wilhelm von Ziemssen's "Handbuch der speciellen Pathologie und Therapie". His "Untersuchungen über den elektrischen Leitungswiderstand des menschlichen Körpers" (1884) was fundamental to the study of electrical diagnostics.His grave is preserved in the Protestant Friedhof III der Jerusalems- und Neuen Kirchengemeinde (Cemetery No. III of the congregations of Jerusalem's Church and New Church) in Berlin-Kreuzberg, south of Hallesches Tor.

Alix Joffroy (16 December 1844, in Stainville – 24 November 1908) was a French neurologist and psychiatrist remembered for describing Joffroy's sign. He studied in Paris, earning his doctorate in 1873, becoming médecin des hôpitaux in 1879 and agrégé in 1880. He worked at the Pitié-Salpêtrière Hospital from 1885 and succeeded Benjamin Ball as professor of clinical psychiatry in 1893.
Jean-Martin Charcot encouraged him to study neurology, and together they demonstrated atrophy of anterior horn cells in the spinal cord in poliomyelitis in 1869.

Antoine Joseph Jobert de Lamballe (17 December 1799 – 19 April 1867) was a French surgeon. He was born at Matignon, studied medicine at Paris, and in 1830 became surgeon at the Hôpital Saint-Louis. He was elected to the Academy of Medicine in 1840 and to the Academy of Sciences in 1856.
Jobert was a brilliant and resourceful operator, best known for his masterly use of autoplastie, the repair of diseased parts by healthy neighboring tissue, and especially for the operation which he styled élitroplastie, an autoplastic cure of vaginal fistula. He wrote:

Traité théorique et pratique des maladies chirurgicales du canal intestinal (1829)
Etudes sur le système nerveux (1838)
Traité de chirurgie plastique (1849)
De la réunion en chirurgie (1864)

Max Jakob (July 20, 1879 – January 4, 1955) was a German physicist known for his work in the field of thermal science.
Born in Ludwigshafen, Germany, Jakob studied engineering at Technical University Munich, from which he graduated in 1903. From 1903 to 1906, he was an assistant to O. Knoblauch at the Laboratory for Technical Physics. In 1910, Jakob embarked on a 25-year career at the Physikalisch-Technische Reichsanstalt in Charlottenburg, Berlin. During this time he founded and directed applied thermodynamics, heat transfer, and fluid flow laboratories.Fleeing Nazi persecution, Jakob left Germany in 1936 and immigrated to the United States, where he became a professor at Armour Institute of Technology (now Illinois Institute of Technology) and a consultant in heat transfer for Armour Research Foundation. There he conducted research, covering areas such as steam and air at high pressure, devices for measuring thermal conductivity, the mechanisms of boiling and condensation, and flow in pipes and nozzles.His many years of teaching, consulting, and writing resulted in contributions to the literature of the profession; nearly 500 books, articles, reviews and discussions have been published based on his research. He has published a number of books in thermal sciences including Elements of Heat Transfer and Insulation (1942) and Heat Transfer (1956).
He is credited with devising the Jakob dimensionless number, aka Jakob number, which is used in phase change heat transfer calculations:

J
a
=

c

p
,
f

(

T

w

−

T

s
a
t

)

h

f
g

{\displaystyle Ja={\frac {c_{p,f}(T_{w}-T_{sat})}{h_{fg}}}}

The Max Jakob Memorial Award, the highest honor in the field of heat transfer, was established in 1961 by the American Society of Mechanical Engineers (ASME) Heat Transfer Division in honor of Jakob.