We present the first avalanche photodiode (APD) successfully fabricated in standard 65nm CMOS technology. The APD operates both in proportional and Geiger mode at -60C to +60C temperature range. The device comprises an octagonal n+p-well junction surrounded by an n-tub guard-ring; its photon detection probability peaks at 450nm with 200mV excess bias and it is above 1% between 350 and 750nm. The dark count rate is 1.5kHz/μm2 at 200mV excess bias, while afterpulsing is less than 1% for a dead time longer than 5μs and timing jitter is better than 235ps. Applications include low-power, ultra-high-speed quantum number generators, time-of-flight 3D image sensors, LIDAR detectors, and time-resolved spectroscopy.