The trial was performed to assess the effects of feeding media consisting of crude olive cake (COC) or processed animal protein (PAP) on the growth rate and the fatty acid composition of Hermetia illucens (black soldier fly) larvae (BSFL). The results showed a significant decrease in length and weight of larvae in the experimental groups reared on media containing 100% of PAP originating from poultry (PAP-P), mixed PAP (PAP-Mx) or COC compared to the control group fed on the basal diet (CON). The replacement of 50% of PAP with basal diet or wood shavings, significantly improved the length and weight of BSFL reared on both kinds of PAP; however not to the values obtained in the CON group. The addition of mineral and vitamin mixture into COC feeding significantly improved the growth of the BSFL, although it also did not attain the results of the basal diet. In comparison to the CON group, experimental groups containing 100% of PAP-P, PAP-Mx or COC were characterized by a decrease in the content of lauric acid and saturated fatty acids, and an increase in the content of oleic acid and monounsaturated fatty acids (MUFA). Especially high content of MUFA was observable in the COC group. The long-chain polyunsaturated fatty acid content was very low in all groups. In conclusion, with the usage of alternative feeding media, like PAP or COC, significant plasticity in the fatty acid profile of Hermetia illucens larvae could be achieved.