Many names for boys (and girls too) can start with either a C or a K. The C and K spellings have become basically interchangeable. Typically, the K spelling is the variation, although that is not always the case. Names such as Cai and Cale have spawned from Kai and Kale. In some cases, both spellings are equally legitimate, such as with Cillian and Killian, or Caspar and Kaspar.
 
Along with Kai and Killian, other boy names that can start with a C or a K in the US Top 1000 include Cairo and Kairo, Cash and Kash, Colton and Kolton, and Crew and Krew. Those in which both spellings are rare include Caius and Kaius, Cato and Kato.
 
The choice of C or K as an initial may reflect your feelings on name style, traditionality, and image. Here, a selection of boy names that work with either C or K as a first letter.

Boy Names That Can Start with a C or a K

Kain is a masculine name that represents an alternative spelling of Cain, one of the most ancient names in Judeo-Christian tradition. In biblical accounts, Cain was the first son of Adam and Eve who famously killed his brother Abel. Despite these challenging associations, the name has persisted throughout history and across cultures. The spelling variant Kain offers a slight modernization that some parents prefer. The name derives from Hebrew origins, possibly meaning "acquired" or "possession." Beyond biblical connections, Kain has appeared in various cultural contexts, including literature, gaming, and music, giving it a multifaceted character. While never extremely common, the name has maintained a steady presence, appealing to parents seeking a short, strong-sounding name with historical depth and a touch of complexity.

Kain

Boy names that can start with the letter C or K, such as Cash and Kash, Cillian and Killian, and Caleb and Kaleb (Page 6)