What are the similarities between Victor Frankenstein and the Ancient Mariner? "Like one who, on a lonely road, Doth walk in fear and dread, ...

The characters are, on the surface, quite dissimilar, in that Victor Frankenstein is highly cultured, wealthy, and a brilliant scientist while the mariner is relatively uneducated, apparently working as an ordinary seaman. Victor's transgressions come from a form of intellectual arrogance in which he uses his vast intellectual gifts to fashion a monster, usurping the role of God. The mariner's transgression seems an act of impulsive stupidity and cruelty, not deliberately thought out at all. 

It is after these turning points, the death of the albatross and the monster's re-entry into Victor's life, that both characters engage in extended travels or quests to redeem themselves for their transgressions. Both stories include polar landscapes, the Arctic in Victor's case and the Antarctic in the mariner's, as scenes of ultimate desolation and danger. Both characters are compulsive storytellers, with their confessions serving as essential parts of their quests for redemption. For both characters, their punishments are both external ones and internal ones of mental agony that eventually bring them to realize the evil nature of their acts and attempt some form of reparation.