Run Brum Crew (Instagram, Twitter) on Mondays at 18:30 from Chamberlain Square (location). The distance is usually 6k. Register at https://groups.runtogether.co.uk/RunBrumCrew
District Run Run Crew (Instagram) on Tuesdays at 18:15 from BrewDog (location). There are usually two choices: either a 5k or 10k. No registration necessary.
Green Heart Runners (Instagram, Twitter) on Tuesdays at 17:30 from outside the Main Library on the University of Birmingham campus (location). The distance is usually 5k. Register at https://groups.runtogether.co.uk/GreenHeartRunners/Runs
City of Birmingham Striders (Instagram) on Thursdays at 18:30 from St. Paul's Square (location). The distance is usually 8k. Register at https://groups.runtogether.co.uk/COBS/runs
ParkRun (https://www.parkrun.org.uk/edgbastonreservoir) on Saturdays 09:00 at Edgbaston Park Reservoir (location).
ParkRun (https://www.parkrun.org.uk/cannonhill/) on Saturdays 09:00 at Cannon Hill Park (location).
Run of a Kind (https://www.runofakindbirmingham.com). They offer a few different running tours based such as Best of Birmingham, Digbeth Street Art, Leafy Brum, etc. Ideal if you're new to Birmingham or have someone visiting you, but there is also lots new to learn even if you're a born and bred Brummie. Check out more on their Instagram page (https://www.instagram.com/runofakindbirmingham)