A Vissian woman who, with her husband the ship's chief engineer, has been assigned a cogenitor so that they can conceive, and who is dismayed when Trip Tucker teaches it to read.
Calla appears in the Enterprise episode Cogenitor, set in 2153. She is married to the chief engineer of a Vissian exploration vessel that Enterprise meets while studying a hypergiant star.
Vissians have three sexes, and a couple can only have a child with the help of a cogenitor, a small minority treated as having no name, education or rights. One has been lodged with Calla and her husband for this purpose.
Calla is friendly towards Trip and happy to socialise with the humans, but sees nothing wrong in how the cogenitor lives. When it asks for asylum after Trip's lessons, she and her husband are distraught, and the cogenitor's later suicide ends their hope of conceiving for the present.