This study investigates the effectiveness of celebrity endorsements versus social media influencer endorsements on consumer perceptions and purchasing intentions, focusing on fitness and beauty products. The research aims to identify the factors influences the relationship between endorsers or influencers and consumer perceptions, specifically examining the roles of reliability and credibility. The data, drawn from participants exposed to fitness and beauty advertisements, were analyzed using repeated-measures ANOVA to assess differences in means across various conditions and Pearson correlation to explore relationships between variables. The findings reveal significant differences in wishful identification, perceived similarity, trustworthiness, expertise, attitude toward the advertisement, attitude toward the product, purchase intention, influencer familiarity, and product-endorser fit between poor fit and good fit conditions for both celebrity and influencer endorsements. Additionally, correlations highlight strong relationships between wishful identification, perceived similarity, trustworthiness, expertise, attitude toward the advertisement, attitude toward the product, purchase intention, influencer familiarity, and product-endorser fit, underscoring their importance in shaping consumer perceptions and behaviors. Overall, this piece provides valuable insights into the mechanisms driving consumer responses to endorsements, offering implications for marketing strategies in the fitness and beauty industries.