Oscar Leroy is Brent's father, the town grouch and habitually wears a green baseball cap. Born in 1941, he founded Corner Gas but retired and left it to Brent. Oscar complains constantly which brings him into conflict with everyone he encounters who he calls "Jackass!" He and Emma squabble frequently and she usually ends up having to deal with the fallout from his actions. Despite this, he truly loves Emma and occasionally, displays affection for her. He's portrayed by Eric Peterson.
After Brent starts lending videos at Corner Gas, Emma forces Oscar to rent one. Emma can't get Oscar to understand where she put tax receipts for Corner Gas. He decides to build he own coffin but once done, he's freaked out.