Place 2 packages of cream cheese, taco-flavored cheese, and margarine in a mixing bowl. Let stand at room temperature for 30 minutes. Add milk to the cheese mixture in the mixing bowl. Beat with an electric mixer on medium speed until combined, stopping the mixer occasionally to scrape the bowl with a rubber spatula. Cover bowl and chill 4 to 24 hours.
Form cheese mixture into a head shape and place on a serving plate. In a bowl, stir the remaining cream cheese until smooth. Spread head with softened cream cheese. Press in tortilla chips for ears. Using wooden toothpicks, attach a pickled whole pepper for nose, pimiento-stuffed olives for eyes, and pepper-stuffed olives for toes. Cut zigzag pieces of sweet pepper for eyebrows. Use shredded beets for hair and press in carrot sticks for teeth. Serve with assorted crackers.