A competitor or rival — someone (or a company) who competes in a field, market, or contest.
新商品は市場の既存の競争者に挑戦することになる。
The new product will challenge the existing competitors in the market.
彼女は最大の競争者を意識して戦略を練った。
She devised a strategy with awareness of her biggest competitor.
価格で競争者と差をつける必要がある。
It's necessary to differentiate oneself from competitors by price.