Seaborgium (Sg) is a synthetic chemical element with atomic number 106. It is named after the American chemist and nuclear scientist Glenn T. Seaborg, who was awarded the Nobel Prize in 1951 for his role in the discoveries of multiple synthetic elements.

Seaborgium is the third of the so called superheavy elements. In fact, it was Seaborg himself who came up with the concept of both actinides, which include elements 89 to 103, and transactinides (the "superheavy elements") ranging from element 104 and onwards.