Oliver is a hard-working tank engine who, with Duck, runs the Crotoonian Seaside Railway. Alongside his brakevan Toad and his two autocoaches Isabel and Dulcie, he's often tasked with local passenger duties (starting with picking up and dropping off passengers and workmen at Gridinia Bay Docks) and goods work on the coastal railway. Although he can be a little overconfident at times, he's aware of his role on the railway, and will admit that each and every day can be somewhat of a new lesson for him. He especially enjoys his runs from the Bartlett Bay Salt Mines, passing by the marinas and coastline towns that travel along the route.
Oliver was seen collecting passengers at Celgreb City Central when Gordon and Farnsworth bickered prior to being sent off to do freight work. Oliver, in a state of alarm, reminded the departing Farnsworth that passengers bound for his line were onboard his trailing coaches. The boastful silver engine then proceeded to dump his coaches on the line, leaving Sir Reginald stuck halfway into the platform. He was later seen passing by the two fighting engines after their derailment at Great Wolf Junction.
Oliver is based on a GWR 14xx Class 0-4-2T.
His paint had faded by the time he was rescued, leaving him in a rusty red colour. After his rescue, he was repainted in NWR apple green with the 1934 GWR crest painted on the sides of his tanks and his number 11 painted on the sides of his cab in yellow.