Sigurd Eysteinsson, also known as Sigurd the Mighty, was the second Jarl of Orkney, appointed by his brother Rognvald Eysteinsson. As a prominent figure in the Viking conquest of northern Scotland, Sigurd's life and exploits are chronicled in the Norse sagas Heimskringla and Orkneyinga. His rise to power followed the Battle of Hafrsfjord, where the Norwegian kingdom was unified, leading to the Orkney and Shetland islands becoming a refuge for exiled Vikings who later conducted raids. Sigurd's territorial expansion extended to the Scottish mainland, where he conquered Caithness and Sutherland, earning him the title "the Mighty." However, his reign ended tragically after a battle with Máel Brigte, resulting in his fatal injury from the buck-toothed ruler's head. Sigurd was buried in Sigurd's Howe, and his death was succeeded by a period of instability in Orkney. His son Guttorm briefly took over before Rognvald appointed his youngest son, Einarr, as the new Earl of Orkney. Sigurd's legacy as a formidable Norse leader and his conquests in Scotland have solidified his place in history.

Sigurd Ferdinand Olson (April 4, 1899 – January 13, 1982) was a well-respected American writer, environmentalist, and advocate for wilderness preservation. Hailing from Chicago, Illinois, Olson spent his formative years in northern Wisconsin, where his passion for the outdoors was nurtured. He became renowned as a wilderness guide in the Quetico-Superior region, and his influential work played a pivotal role in the protection of the Boundary Waters Canoe Area Wilderness. Olson's dedication to environmental causes extended to his involvement in drafting the Wilderness Act of 1964 and his role as vice-president and president of The Wilderness Society. His efforts also contributed to the establishment of Voyageurs National Park in Minnesota and Alaska's Arctic National Wildlife Refuge. Olson's significant impact was recognized with the John Burroughs Medal in 1974. His legacy lives on through the Sigurd Olson Environmental Institute and the preservation of his cabin on Burntside Lake, which is now listed on the National Register of Historic Places. With a lasting dedication to the natural world, Olson's influence continues to inspire conservation efforts and the appreciation of wilderness.

Sigurd Lewerentz (29 July 1885 – 29 December 1975) was a renowned Swedish architect known for his influential contributions to modernist architecture. He initially trained as a mechanical engineer at Chalmers University of Technology in Gothenburg before pursuing an architectural apprenticeship in Germany. Lewerentz established his own architectural office in Stockholm in 1911 and later collaborated with the distinguished architect Gunnar Asplund. Together, they won the Stockholm South (Woodland) Cemetery competition in 1914–15.Throughout his career, Lewerentz's architectural designs were characterized by their daring and rugged use of materials, creating an indefinable atmosphere and sense of place. His notable works include the Malmö Opera and Music Theatre, as well as the churches St. Mark's at Björkhagen in Stockholm and St. Peter's at Klippan in Scania. Despite briefly turning away from architecture to run a factory, Lewerentz's later churches revived his career, showcasing his unique approach to space, light, and materiality.Lewerentz's legacy continues to be celebrated for its high quality and innovation in architectural design. His contributions have been extensively studied and commemorated in various publications and peer-reviewed journal articles, reflecting his enduring influence on the architectural landscape.

Sigurd Hauso Haugen, born on 17 July 1997, is a Norwegian professional footballer known for his role as a forward for 3. Liga side Hansa Rostock, where he is currently on loan from Danish Superliga club AGF. Haugen signed a five-year contract with AGF on 7 July 2022 and made his competitive debut on 17 July. He scored his first goal for AGF on 24 July, along with providing an assist. Subsequently, he joined NAC Breda in the Netherlands on loan with an option to buy in August 2023. In September 2024, he joined Hansa Rostock on a loan deal until the end of the 2024–25 season. In December 2022, Haugen was involved in an incident in Aarhus, where he was arrested after an altercation with a doorman outside a disco, although he was not charged and was released the following day. Haugen's career statistics are notable, and his professional journey continues to unfold.

Sigurd Hole, born on July 13, 1981, is a renowned Norwegian jazz musician known for his mastery of the upright bass. Hailing from Rendalen and currently based in Oslo, Hole has made significant contributions to the jazz and Norwegian folk music scenes. Notably, he has received two Norwegian Grammy nominations in recent years. In January 2018, Hole debuted his first solo double bass album titled "Elvesang," which beautifully blends classical minimalism, Norwegian musical heritage, and the enchanting sound of the Japanese Shakuhachi flute. The album received high praise, earning a spot on the prestigious Best of 2018 lists by All About Jazz and The New York City Jazz Record. Furthermore, Hole is set to release another solo double bass album titled "Lys / Mørke" in February 2020. With his trio, the Sigurd Hole Trio, he released the album "Encounters" in 2018, which garnered critical acclaim worldwide. Hole's musical prowess extends beyond his solo and trio work, as he has been an integral part of various ensembles and collaborations, showcasing his versatility and artistry. In addition to his musical endeavors, Hole has also shared his knowledge and expertise as a teacher at the Norwegian Academy of Music. With an impressive discography and a global presence, Sigurd Hole continues to captivate audiences with his unique blend of musical traditions and innovative expressions.