Antonyms for the word "attestors" would be words that denote the opposite or the absence of attesting qualities. Some possible antonyms include words such as deniers, refuters, contradictors, challengers, opposers, skeptics, disbelievers, or dissenters. These words indicate a lack of agreement, support, or confirmation, and suggest skepticism, doubt, or disagreement. Unlike attestors, who affirm or certify something as true or valid, antonyms convey the opposite or contradicting meaning. While attestors provide evidence and testify to the veracity of a statement or claim, antonyms challenge or reject it, either because of lack of information, suspicion, or disagreement.