The Red-tailed Bumblebee (Bombus lapidarius) is probably the most easily recognised bumblebee species, with its black body and bright orange tail.
The females (worker bees) have the same colouring as the queen (20-22 mm) but are much smaller (11-16 mm).
The males (14-16 mm) also have similar colouring but have a yellow collar (some yellow hairs in the neck and chest).

1st, 2nd & 3rd photo: A queen (it is huge!). In my yard, Hilversum, The Netherlands, 14 August 2018
4th photo: A male. 's Graveland, The Netherlands, 11 July 2011
5th photo: Laagraven Plas, Utrecht, The Netherlands, 24 July 2021