var result1 = (from a in list1
                           from b in list2
                           where a.CreatorId == b.Id
                           select new Result
                           {
                               Id = a.Id,
                               Name = b.Name
                           }).Concat(from a in notcontainId
                                     from b in list1
                                     where a == b.CreatorId
                                     select new Result
                                     {
                                         Id = a,
                                         Name = null
                                     });