using System;
using System.Collections.Generic;
using System.Linq;

    public class EmployeeDto
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }

    public class EmployeeEntity
    {
        public int Id { get; set; }
        public string FullName { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            List<object> o = new List<object>();
            o.Add(new EmployeeDto { Id = 1, Name = "Bob" });
            o.Add(null);
            o.Add(new EmployeeDto { Id = 2, Name = "Foo" });
            o.Add(null);
            o.Add(null);

            var employeeEntityList = MapList1(o);
            var employeeEntityList2 = MapList2(o);

            PrintEmployee(employeeEntityList);
            Console.WriteLine("--");
            PrintEmployee(employeeEntityList2);

            Console.ReadKey();
        }

        private static void PrintEmployee(IEnumerable<EmployeeEntity> employeeEntityList)
        {
            foreach (var item in employeeEntityList)
            {
                Console.WriteLine(item.FullName);
            }
        }

        private static IEnumerable<EmployeeEntity> MapList1(List<object> o)
        {
            return
                from i in o.OfType<EmployeeDto>()
                select new EmployeeEntity
                {
                    Id = i.Id,
                    FullName = i.Name
                };
        }

        private static IEnumerable<EmployeeEntity> MapList2(List<object> o)
        {
            return
                from si in o
                let i = si as EmployeeDto
                where i != null
                select new EmployeeEntity
                {
                    Id = i.Id,
                    FullName = i.Name
                };
        }
    }