Jessica Mogardo is very notable for competing (and winning!) on Chopped and being Jose Garces' sous chef in Iron Chef America. Like her appearances on the other competitions, she won!
Alina Eisenhauer also competed, but lost on Chopped. She ended up winning Sweet Genius.
Katie Rosenhouse lost twice on Chopped but won on Sweet Genius likewise. However, she Took a Level in Jerkass, pouting about how she wanted to win the other competition. She didn't mention Chopped by name, but it was clear which competition she was talking about.
Like the chefs above, Natalia Machado has appeared on Chopped (in which she won), and won Sweet Genius
One rather large chef in the first season became part of a Food Network profile in Fat Chef.