Obi Chamberlain is a 6’7” one-foot dunker with an 8’6” standing reach and a 42 inch running vertical. He takes off from his left foot.
The 8’6” reach is the largest on this site. Standing flat-footed he is six inches under the rim, which means a 42 inch vertical puts his hand around twelve feet, roughly two feet of clearance above the ring. That much room changes what is possible in the air: the constraint stops being whether the ball gets there and becomes what he can do on the way.
His signature is a cuffed free-throw-line dunk, which uses the clearance directly. Cuffing means holding the ball pinned against the forearm rather than palmed, so it cannot be adjusted mid-flight, and taking off from the line adds fifteen feet of horizontal travel. A one-foot takeoff is the right approach for that dunk, since it preserves the run-in speed that a two-foot gather would kill.
He is on the shortlist for the Dunker Survey, which only takes jumpers with a verified 40 inch vertical or better.
Tall one-foot dunkers are the rarest profile in the sport. Most dunkers over 6’6” end up as power dunkers because the reach makes rotation unnecessary, and most one-foot specialists are shorter, because the single-leg takeoff suits a lighter frame. Chamberlain is both.