Background: Online sexual harassment in adolescence is associated with depressive symptoms. There is, however, a dearth of research investigating variability of symptom profiles in this population in relation to offender gender and age. Objective: To identify the proportion of adolescents reporting online harassment by different types of offenders and compare their levels of depression. Participants and setting: Participants were 18,872 Chilean students aged 12 to 17 years (3.063 of them online sexually harassed). Methods: The study involved a secondary analysis of self-report data on online sexual harassment, poly-victimization, and depression collected as part of the National Poly-victimization Survey. Results: In 37.6% of the cases the offender was male under 18, in 22.4% an adult male, in 14.5% a female under 18, and in 2.9% an adult female. In 22.5% of cases the offender could not be identified. An ANCOVA demonstrated levels of poly-victimization across the lifespan and frequency of online sexual harassment in the last year to predict depressive symptomatology. In females, higher levels of depressive symptoms were observed among those sexually harassed by either a female under 18, an offender whose age and gender the victim could not identify, or an adult male. In males, higher levels of depression were observed among those harassed by either an adult male, an offender whose age and gender the victim could not identify, or a male under 18. Conclusions: The current study highlights the importance of offender's age and gender in predicting depression levels in adolescent victims of online sexual harassment.