What is a cell that provides energy for another organism called?

A cell that provides energy and biological support for another organism is called a host cell.

In biology, a host cell is the cell occupied or used by another organism, especially a virus. Viruses cannot make their own proteins or reproduce independently, so they enter a host cell and redirect some of its molecular machinery. The host supplies resources such as energy, nucleotides, amino acids, and enzymes that the virus needs to copy its genetic material and build new virus particles.

The term is most commonly used in virology, but the broader idea also applies to other relationships in which one organism lives in or depends on another. A host cell should not be confused with a mitochondrion, which produces ATP for its own cell, or with a producer, such as a plant, which captures energy for an ecosystem through photosynthesis.

Host cells are not always harmed in exactly the same way. Some viruses rapidly destroy them, while others establish long-term infections or remain dormant. The exact effects depend on the virus, the host species, and the cell type involved.