Best supercross rider of all time is a stadium question. Motocross nationals are a different series. If you want outdoor GOAT, that is Ricky Carmichael on combined AMA titles. If you want who owned the dirt inside a football stadium, the record still starts with Jeremy McGrath.
“Best supercross riders of all time” (plural) is the same search with a longer list. Start with wins and 450/250 premier titles. Do not start with last weekend’s main.
Jeremy McGrath
Seven AMA 250 supercross championships: 1993 through 1996, then 1998, 1999, 2000. Seventy-two wins in the premier supercross class, still the mark. Two 125 West titles before that. Two FIM supercross world titles. One 250 outdoor national (1995). He is called King of Supercross because the win column in stadiums is his. The jumping style (lower, earlier) is still what kids copy.
Ricky Carmichael
Five premier supercross titles, 48 premier supercross mains in the usual Hall of Fame split, 15 AMA championships when you add motocross. Three undefeated outdoor seasons at the top level (2002, 2004, 2005) per the AMA Motorcycle Hall of Fame. If the question is “best motorcycle racer in AMA dirt,” Carmichael wins a lot of rooms. If the question is strictly supercross mains, McGrath still has the bigger number.
After those two
James Stewart: peak speed, high win percentage in the races he finished, championships cut short by injury. Chad Reed: longevity, titles, the rider who would not leave. Ryan Villopoto: a short, stacked premier peak in both SX and MX. Eli Tomac: modern combined-win hunter. Jett Lawrence is the active Honda reference; “of all time” is premature.
450 supercross and 250 East/West are different classes. A 250 regional title is not a 450 ring. When a graphic says “most supercross wins” check whether Lites/250 mains are mixed in.
We already covered famous motocross riders as an outdoor-plus-combined list. This page is the stadium half. Same dirt, different scoreboard.