Why is the kelvin temperature unit named after William Thomson?

The kelvin temperature unit is named after the British physicist William Thomson, who was later known as Lord Kelvin.12

In 1848, Thomson proposed an absolute temperature scale that utilized the Celsius degree but was anchored to absolute zero, the theoretical point at which molecular energy is at its lowest. Because this scale—now the international standard for scientific temperature measurement—is named the Kelvin scale, the fundamental unit of measurement derived from it was subsequently named the kelvin.12