|Elevation||222 m (728 ft)|
|Time zone||EST (UTC-5)|
|• Summer (DST)||EDT (UTC-4)|
|Area code(s)||905 and 289|
Cashel, Ontario is a small hamlet situated in Unionville, Ontario located at the intersection of Elgin Mills Road and York Regional Road 67. Originally it was called Crosby Corners after John Crosby (born 1797), the village's first store owner, who came originally from New York State. The name was changed to Cashel in 1851 with the opening of its first post office. It was likely named after Cashel in Ireland. In 1851 the community had a sawmill, cobbler shop, blacksmith shop, wagon shop, inn and tavern, Masonic Lodge, and Presbyterian church. 
There are few dwellings located at the site, most of them near York Regional Road 3, the western boundary of this community. Other parts of the community is mainly farmlands. Cashel's northern boundary is the town of Whitchurch–Stouffville. The community is home to the Markham Fairgrounds.
- Stouffville, north
- Quartztown, south
- Historical Village of Markham, south-east
- Angus Glen, south-west
- Victoria Square, west
- Uxbridge, east
- For a fuller account of Cachel's history, cf. Isabel Champion, ed., Markham: 1793-1900 (Markham, ON: Markham Historical Society, 1979), pp. 233-235. See also the detailed 1878 map, "Township of Markham," Illustrated historical atlas of the county of York and the township of West Gwillimbury & town of Bradford in the county of Simcoe, Ont. (Toronto: Miles & Co., 1878).
- Cf. I. Champion, ed., Markham: 1793-1900 (Markham, ON: Markham Historical Society, 1979), pp. 266-270.
|Angus Glen, Ontario||Dickson Hill, Ontario
Markham Village, Ontario