Option 1 - Image Role

Starting in Tableau Desktop 2022.4, it is possible to assign a field containing URLs for web-hosted images the image role, which will render the images in a row or column header. See Add Web Images Dynamically to Worksheets for instructions 

Option 2 - URL Action

1. From the Dashboard pane, drag Web Page onto your dashboard to create a dynamic web page window.
2. Navigate to Dashboard > Actions.
3. Select Add Action > URL.
4. Under Run action on: choose Select.
5. Click on the triangle to the right of the URL field and select the name of the column that contains the image URLs.
6. Click on OK.

Option 3 - Parameter Selection

1. Create a new parameter with a data type of string.
2. From the Add from Field button choose the field containing all or part of the URL address that is hosting the images and click OK.
3. Open a new Dashboard and show the parameter, Analysis > Parameters > [Parameter Name].
4. From the Objects pane in the bottom corner drag a Web Page onto the view.
5. In the window that appears there will be an option to enter the Web URL Address, 
   • If the parameter contains the full URL address then simply insert the parameter from the right hand arrow 
   • Or, if the parameter contains just part of the URL address, such as the name of the image, then type out the part of the URL address in this window and insert the parameter to complete it, ex. www.hostedimages.com/<parameter>