Their heights are semi-known, but not totally confirmed. From the same website that had the ages correctly listed for years before Blizzard confirmed them (with a few exceptions like estimated ages for the new heroes).
Anyway these are their known and estimated heights:
2.23m/7ft 4” – Reinhardt, Orisa (Estimated)
2.20m/7ft 3” – Bastion and Roadhog (also Winston when standing upright)
2.18m/7ft 1” – Doomfist
2.13m/7ft – Junker Queen, Lifeweaver (Estimated)
1.96m/6ft 6” – Junkrat
1.95m/6ft 5” – Zarya, Moira (Estimated)
1.93m/6ft 4” – Ramattra
1.91m/6ft 3” – Brigitte (Estimated)
1.89m/6ft 2.5” – Baptiste (Estimated)
1.85m/6ft 1” – Reaper, Soldier: 76, Cassidy
1.82m/6ft – Ana, Echo (Estimated)
1.80m/5ft 11” – Pharah, Sojourn (Estimated)
1.75m/5ft 9” – Widowmaker
1.73m/5ft 8” – Hanzo
1.72m/5ft 7.5” – Zenyatta
1.70m/5ft 7” – Mercy, Symmetra (also Winston when standing normally), Genji, Kiriko (Estimated)
1.67m/5ft 6″ – Ashe
1.66m/5ft 5” – D.Va (mechless)
1.62/5ft 4” – Tracer, Sombra
1.60m/5ft 3” – Lucio, Mei
1.40m/4ft 7” – Torbjörn
40cm/1ft 4” – Hammond (without wrecking ball)
As a woman who is only 5’0" tall, it always struck me how absolutely enormous some of the OW women are. Ana, Brig, Moira and especially JQ, for example. Big, big ladies.