OpenLayers 2 : OpenStreetMap and Google
OpenLayers 2 : OpenStreetMap and Google with BGS and RoW
OpenLayers 2 : OpenStreetMap and IGN France
OpenLayers 2 : OpenStreetMap and IGN Spain
OpenLayers 2 : OS Maps with BGS and RoW

OpenLayers 3+ : OpenStreetMap and Google
OpenLayers 3+ : OpenStreetMap and Google with BGS, RoW and contours
OpenLayers 3+ : OpenStreetMap and IGN France in RGF projection
OpenLayers 3+ : OpenStreetMap and OS Open Zoomstack
OpenLayers 3+ : OpenStreetMap in UTM projection
OpenLayers 3+ : OpenStreetMap with contours in UTM projection
OpenLayers 3+ : OS Vector Tiles
OpenLayers 3+ : OS Maps and Vector Tiles

OpenLayers 6 : OS Vector Tiles with Mapbox GL
OpenLayers 6 : OS Maps and Vector Tiles with Mapbox GL