So far, a lot of work has been done on the characterization of distributions. In this article, we characterize a lifetime random variable following any distribution among two-parameter Weibull, modified Weibull, modified Weibull extension, log-logistic, modified log-logistic, power Lomax, modified power Lomax, and inverse two-parameter Weibull distributions. The functions, viz., failure rate, reversed failure rate, aging intensity, reversed aging intensity, and log odds rate, available in reliability theory, along with the recently introduced concepts of generalized aging intensity and generalized reversed aging intensity functions, are used in the analysis.