A hydrocarbon conversion process, comprising: (a) providing a first mixture comprising ≥ 10.0 wt. % hydrocarbon based on the weight of the first mixture; (b) pyrolysing the first mixture to produce a second mixture comprising ≥ 1.0 wt. % of C 2 unsaturates and ≥ 1.0 wt. % tar, the weight percents being based on the weight of the second mixture; (c) separating a tar stream from the second mixture, wherein the tar stream contains ≥ 90 wt. % of the second mixture's molecules having an atmospheric boiling point of ≥ 290°C; (d) providing a utility fluid, the utility fluid comprising ≥ 1.0 wt. % aromatics based on the weight of the utility fluid; (e) providing a hydrogen stream comprising molecular hydrogen; (f) heating the tar stream to a bulk temperature below 300°C by one or more of (i) exposing the tar stream to a temperature in the range of 200.0°C to 400.0°C, (ii) exposing the utility fluid to a temperature ≥ 400.0°C and then combining the tar stream with the heated utility fluid, and/or (iii) exposing the hydrogen stream to a temperature ≥ 400.0°C and then combining the tar stream with the heated hydrogen stream; and (g) hydroprocessing in the hydroprocessing zone at least a portion of the heated tar stream at a temperature of from 350°C to 430°C in the presence of (i) the hydrogen stream and/or heated hydrogen stream and (ii) the utility fluid and/or the heated utility fluid under catalytic hydroprocessing conditions at a utility fluid:tar stream weight ratio in the range of 0.05 to 3.0 to produce a hydroprocessed product, wherein the utility fluid comprises the hydroprocessed product in an amount ≥ 10.0 wt. % based on the weight of the utility fluid. (a) providing a first mixture comprising ≥ 10.0 wt. % hydrocarbon based on the weight of the first mixture; (b) pyrolysing the first mixture to produce a second mixture comprising ≥ 1.0 wt. % of C 2 unsaturates and ≥ 1.0 wt. % tar, the weight percents being based on the weight of the second mixture; (c) separating a tar stream from the second mixture, wherein the tar stream contains ≥ 90 wt. % of the second mixture's molecules having an atmospheric boiling point of ≥ 290°C; (d) providing a utility fluid, the utility fluid comprising ≥ 1.0 wt. % aromatics based on the weight of the utility fluid; (e) providing a hydrogen stream comprising molecular hydrogen; (f) heating the tar stream to a bulk temperature below 300°C by one or more of (i) exposing the tar stream to a temperature in the range of 200.0°C to 400.0°C, (ii) exposing the utility fluid to a temperature ≥ 400.0°C and then combining the tar stream with the heated utility fluid, and/or (iii) exposing the hydrogen stream to a temperature ≥ 400.0°C and then combining the tar stream with the heated hydrogen stream; and (g) hydroprocessing in the hydroprocessing zone at least a portion of the heated tar stream at a temperature of from 350°C to 430°C in the presence of (i) the hydrogen stream and/or heated hydrogen stream and (ii) the utility fluid and/or the heated utility fluid under catalytic hydroprocessing conditions at a utility fluid:tar stream weight ratio in the range of 0.05 to 3.0 to produce a hydroprocessed product, wherein the utility fluid comprises the hydroprocessed product in an amount ≥ 10.0 wt. % based on the weight of the utility fluid.