Okotoks Erratic, Glacial erratic in Foothills County, Canada.

Okotoks Erratic is a quartzite boulder in Foothills County, Canada, that extends 41 meters in length while rising 9 meters high and measuring 18 meters across. Its pale rock stands out against the surrounding grassland and shows pink and purple tones that shift in intensity depending on the light.

Between 12,000 and 17,000 years ago a landslide in the upper Athabasca River valley dropped quartzite onto a valley glacier, which carried it east and then south along the Rockies. When the ice melted, the load was set down as the Foothills Erratics Train. James Hector of the Palliser Expedition first documented the rock in 1863 and mistook it for a klippe.

The Blackfoot name is o'kotok, meaning "rock", which also gave the town of Okotoks its name. A Blackfoot story tells that Napi, the trickster, left his robe on the rock; when he took it back, the rock rolled after him and broke in two when bats struck it. The split also explains the bats' flattened faces.

The site sits right along Highway 7 with its own parking area, from which the boulder can be reached in a few steps. The open location allows visits in any season, with early morning and late afternoon offering particularly good light for observation.

The quartzite composition can be traced back to a mountain range now more than 300 kilometers to the northwest. The characteristic cracks in the rock formed through repeated freezing and thawing of water in its natural joints, a process that continues to be active.