pope from 283 (possibly December 17) to 296. Nothing about him is known with certainty. Supposedly a relative of the Roman emperor Diocletian, he conducted his pontificate at a period of Diocletian's reign when Christians were tacitly tolerated. Gaius is said, nevertheless, to have carried on his religious work for his last eight years concealed in the catacombs. His epitaph was found in the Cemetery of Calixtus.