The present disclosure relates to semiconductor structures and, more particularly, to a lateral bipolar transistor with gated collector and methods of manufacture. The structure includes: an extrinsic base region vertically over a semiconductor substrate and comprising asymmetrical sidewall spacers on opposing sidewalls of the extrinsic base region; a collector region on the semiconductor substrate and separated from the extrinsic base region by at least a first spacer of the asymmetrical sidewall spacers; and an emitter region on the semiconductor substrate and separated from the extrinsic base region by a second spacer of the asymmetrical sidewall spacers.