D'Ambrose is unavoidable--regular theatergoers are liable to see him onstage a half-dozen times per year in an amazing variety of venues. This past year, the lanky, wry performer has graced the stage of the Park Square Theatre, the Loring Playhouse, the Mixed Blood Theatre, and, most notably, the Jungle Theater. D'Ambrose's role there was in a production called The Pavilion, essentially a sweet two-character romance about former lovers rooting through their pasts at a high school reunion. D'Ambrose narrated the story, as well as playing any incidental character that was needed, regardless of gender. This offered him an opportunity to dazzle, racing across the stage to switch, sometimes in midsentence, from a stoned city mayor to a bitter, chain-smoking divorcée--all accomplished by nothing more elaborate than a shift in posture and vocal tone. But he is also an actor with quiet authority, which is why, despite his comic chops, he is often cast in roles like Mr. Frank in the Park Square production of The Diary of Anne Frank. This is a part that is both underwritten and saintly, and D'Ambrose brought to it a hollowness of expression and gravity of bearing that suggested a man shattered by the Holocaust--a great, tragic performance in a play that is written more like a situation comedy.