It's difficult to pinpoint a single person who "discovered" wavelength. It's a concept that developed over time through the work of many scientists. However, a few key figures contributed significantly to our understanding of wavelength:

* Isaac Newton: While Newton didn't use the term "wavelength," his experiments with prisms in the 17th century laid the groundwork for understanding the separation of white light into its constituent colors. This is fundamentally linked to the different wavelengths of light.

* Thomas Young: In the early 19th century, Young performed his famous double-slit experiment. This experiment demonstrated the wave nature of light and provided a way to measure the wavelength of different colors.

* Augustin-Jean Fresnel: Building on Young's work, Fresnel further developed the wave theory of light. He derived mathematical equations to describe the behavior of light waves, including their wavelength.

Therefore, while we can't point to a single "discoverer," these individuals and their work were crucial in developing the concept of wavelength and its significance in understanding light.