Thermococcus celer is a species of extremely thermophilic Archaea, and the type species for Thermococcus. For optimal growth it requires a temperature of 85 °C. T. celer is an organotrophic organism. It needs a source of sulphur to thrive. In the laboratory it was found to be unable to use maltose as a carbon source and required to be provided with peptides. Like many other archaea, T. celer is a strict anaerobe.
The chromosome of T. celer is a single, circular DNA molecule, with 1,890±27 kilobase pairs. A gene from Thermococcus celer has been identified and sequenced that appears to encode a transcription-associated protein. The protein translations of this gene is a homolog of a small subunit found in eukaryotic RNA polymerase I. This provides evidence that eukaryotes are more related to the Archaea that to bacteria.