• Physicist Wilhelm Conrad Röntgen, 1845
  

Röntgen was born in a traditional Catholic family in Lennep, Germany, as the only child of a merchant and manufacturer of cloth. His mother was Charlotte Constanze Frowein of Amsterdam. In March 1848, the family moved to Apeldoorn and Wilhelm was raised in the Netherlands. He received his early education at the boarding school, Institute of Martinus Herman van Doorn, in Apeldoorn. From 1861 to 1863, he attended the ambachtsschool in Utrecht. He was expelled for refusing to reveal the identity of a classmate guilty of drawing an unflattering portrait of one of the school's teachers. Not only was he expelled, he subsequently found that he could not gain admittance into any other Dutch or German gymnasium.

In 1865, he tried to attend the University of Utrecht without having the necessary credentials required for a regular student. Upon hearing that he could enter the Federal Polytechnic Institute in Zurich (today known as the ETH Zurich), he passed its examinations, and began studies there as a student of mechanical engineering. In 1869, he graduated with a Ph.D. from the University of Zurich; once there, he became a favorite student of Professor August Kundt, whom he followed to the University of Strassburg in 1873.

In 1874 Röntgen became a lecturer at the University of Strassburg. In 1875 he became a professor at the Academy of Agriculture at Hohenheim, Württemberg. He returned to Strassburg as a professor of physics in 1876, and in 1879, he was appointed to the chair of physics at the University of Giessen. In 1888, he obtained the physics chair at the University of Würzburg, and in 1900 at the University of Munich, by special request of the Bavarian government. Röntgen had family in Iowa in the United States and at one time planned to emigrate. Although he accepted an appointment at Columbia University in New York City and had actually purchased transatlantic tickets, the outbreak of World War I changed his plans and he remained in Munich for the rest of his career.

During 1895 Röntgen was investigating the external effects from the various types of vacuum tube equipment — apparatuses from Heinrich Hertz, Johann Hittorf, William Crookes, Nikola Tesla and Philipp von Lenard — when an electrical discharge is passed through them. In early November, he was repeating an experiment with one of Lenard's tubes in which a thin aluminum window had been added to permit the cathode rays to exit the tube but a cardboard covering was added to protect the aluminum from damage by the strong electrostatic field that is necessary to produce the cathode rays. He knew the cardboard covering prevented light from escaping, yet Röntgen observed that the invisible cathode rays caused a fluorescent effect on a small cardboard screen painted with barium platinocyanide when it was placed close to the aluminum window. It occurred to Röntgen that the Hittorf - Crookes tube, which had a much thicker glass wall than the Lenard tube, might also cause this fluorescent effect.

In the late afternoon of 8 November 1895, Röntgen determined to test his idea. He carefully constructed a black cardboard covering similar to the one he had used on the Lenard tube. He covered the Hittorf - Crookes tube with the cardboard and attached electrodes to a Ruhmkorff coil to generate an electrostatic charge. Before setting up the barium platinocyanide screen to test his idea, Röntgen darkened the room to test the opacity of his cardboard cover. As he passed the Ruhmkorff coil charge through the tube, he determined that the cover was light - tight and turned to prepare the next step of the experiment. It was at this point that Röntgen noticed a faint shimmering from a bench a meter away from the tube. To be sure, he tried several more discharges and saw the same shimmering each time. Striking a match, he discovered the shimmering had come from the location of the barium platinocyanide screen he had been intending to use next.

Röntgen speculated that a new kind of ray might be responsible. 8 November was a Friday, so he took advantage of the weekend to repeat his experiments and make his first notes. In the following weeks he ate and slept in his laboratory as he investigated many properties of the new rays he temporarily termed "X-rays", using the mathematical designation for something unknown. Although the new rays would eventually come to bear his name in many languages as "Röntgen Rays" (and the associated X-ray radiograms as "Röntgenograms"), he always preferred the term X-rays.

Nearly two weeks after his discovery, he took the very first picture using X-rays of his wife's hand, Anna Bertha. When she saw her skeleton she exclaimed "I have seen my death!"

The idea that Röntgen noticed the shimmering of the barium platinocyanide screen simply through good fortune misrepresents his investigative powers; he had planned to use the screen in the next step of his experiment and would therefore have made the discovery a few moments later regardless.

At one point while he was investigating the ability of various materials to stop the rays, Röntgen brought a small piece of lead into position while a discharge was occurring. Röntgen thus saw the first radiographic image, his own flickering ghostly skeleton on the barium platinocyanide screen. He later reported that it was at this point that he determined to continue his experiments in secrecy, because he feared for his professional reputation if his observations were in error.

Röntgen's original paper, "On A New Kind Of Rays" (Über eine neue Art von Strahlen), was published on 28 December 1895. On 5 January 1896, an Austrian newspaper reported Röntgen's discovery of a new type of radiation. Röntgen was awarded an honorary Doctor of Medicine degree from the University of Würzburg after his discovery. He published a total of three papers on X-rays between 1895 and 1897. Today, Röntgen is considered the father of diagnostic radiology, the medical specialty which uses imaging to diagnose disease.

Röntgen was married to Anna Bertha Ludwig (m. 1872, d. 1919) and had one child, Josephine Bertha Ludwig. Adopted at age 6, in 1887, she was the daughter of Anna's brother. Röntgen died on 10 February 1923 from carcinoma of the intestine. It is not believed his carcinoma was a result of his work with ionizing radiation because of the brief time he spent on those investigations, and because he was one of the few pioneers in the field who used protective lead shields routinely. In keeping with his will, all his personal and scientific correspondence were destroyed upon his death.

In 1901 Röntgen was awarded the very first Nobel Prize in Physics. The award was officially "in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him". Röntgen donated the monetary reward from his Nobel Prize to his university. Like Pierre Curie, Röntgen refused to take out patents related to his discovery, as he wanted mankind as a whole to benefit from practical applications of the same (personal statement). He did not even want the rays to be named after him.

• Rumford Medal (1896)
• Matteucci Medal (1896)
• Elliott Cresson Medal (1897)
• Nobel Prize for Physics (1901)
• In November 2004 IUPAC named element number 111 Roentgenium (Rg) in his honour. IUPAP also adopted the name in November 2011.

Today, in Remscheid - Lennep, 40 kilometers east of Düsseldorf, the house in which Roentgen was born in 1845 is the Deutsches Röntgen - Museum.

In many languages, Röntgen's name (or a local linguistic derivative) is used to refer to radiology and its products instead of the term "X-ray", which Röntgen himself coined, for example Japanese "rentogen", the Lithuanian "rentgeno", the Hebrew "rentgen", the Croatian "rentgen", and Turkish "röntgen".

The Philips Medical System diagnostic radiography research and development division in Hamburg DE is on Röntgenstrasse (Röntgen Street).