Methods and systems for hydroprocessing heavy oil feedstocks to form an upgraded material involve the use of a colloidal or molecular catalyst dispersed within a heavy oil feedstock, a pre-coking hydrocracking reactor, a separator, and a coking reactor. The colloidal or molecular catalyst promotes upgrading reactions that reduce the quantity of asphaltenes or other coke forming precursors in the feedstock, increase hydrogen to carbon ratio in the upgraded material, and decrease boiling points of hydrocarbons in the upgraded material. The methods and systems can be used to upgrade vacuum tower bottoms and other low grade heavy oil feedstocks. The result is one or more of increased conversion level and yield, improved quality of upgraded hydrocarbons, reduced coke formation, reduced equipment fouling, processing of a wider range of lower quality feedstocks, and more efficient use of supported catalyst if used in combination with the colloidal or molecular catalyst, as compared to a conventional hydrocracking process or a conventional thermal coking process.