asp.net mvc. Passing a list via viewData

You need to cast it in the view:

<% var galList = ViewData["SomeList"] as List<myNS.CM.AVDTalentApplication.Models.GalleryModel>;  %>

or

<% var galList = (List<myNS.CM.AVDTalentApplication.Models.GalleryModel>) ViewData["SomeList"];  %>

For this line:

List<myNS.CM.AVDTalentApplication.Models.GalleryModel> galList = ViewData["SomeList"];

change it to

var galList = ViewData["SomeList"] as List<myNS.CM.AVDTalentApplication.Models.GalleryModel>;