Noun
someone who performs with an eye to the applause from spectators in the grandstand
Source: WordNetIndeed, he quickly drew criticisms from lawyers involved — The New York Times, while shadowing him for a day, overheard counsel calling him a "grandstander" and "Pollyanna" — and from the legal community at-large keenly following the proceedings. Source: Internet
Reiner thrived on publicity, and knew how to get it; he was a grandstander. Source: Internet