Unity Script Generated by ScripterAI

"Functional Complex Character Controller with built in camera system that uses RigidBody. Footsteps system, headbobbing, Stamina system (With running), Jump, crouch, breathing system when sprinting, no stamina or stamina not in use and Grounding."

This is a complex character controller with many features. I'll provide you with a basic template, but you'll need to customize and expand it according to your needs.

```csharp
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ComplexCharacterController : MonoBehaviour
{
    public float walkSpeed = 2;
    public float runSpeed = 6;
    public float crouchSpeed = 1;
    public float acceleration = 5;
    public float jumpForce = 5;
    public float stamina = 100;
    public float staminaRecovery = 5;
    public float staminaConsumption = 10;
    public bool isGrounded;
    public Transform groundCheck;
    public LayerMask groundMask;
    public float groundDistance = 0.4f;

private Rigidbody rb;
    private Vector3 moveDirection;
    private float speed;
    private bool isRunning;
    private bool isCrouching;
    private float currentStamina;

void Start()
    {
        rb = GetComponent<Rigidbody>();
        currentStamina = stamina;
    }

void Update()
    {
        isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);

float horizontal = Input.GetAxis("Horizontal");
        float vertical = Input.GetAxis("Vertical");

moveDirection = new Vector3(horizontal, 0, vertical).normalized;

if (Input.GetKey(KeyCode.LeftShift) && !isCrouching && currentStamina > 0)
        {
            isRunning = true;
            currentStamina -= staminaConsumption * Time.deltaTime;
        }
        else
        {
            isRunning = false;
            currentStamina += staminaRecovery * Time.deltaTime;
        }

currentStamina = Mathf.Clamp(currentStamina, 0, stamina);

if (Input.GetKeyDown(KeyCode.Space) && isGrounded)
        {
            rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
        }

if (Input.GetKeyDown(KeyCode.C))
        {
            isCrouching = !isCrouching;
        }

if (isCrouching)
        {
            speed = Mathf.Lerp(speed, crouchSpeed, acceleration * Time.deltaTime);
        }
        else if (isRunning)
        {
            speed = Mathf.Lerp(speed, runSpeed, acceleration * Time.deltaTime);
        }
        else
        {
            speed = Mathf.Lerp(speed, walkSpeed, acceleration * Time.deltaTime);
        }
    }

void FixedUpdate()
    {
        rb.MovePosition(rb.position + transform.TransformDirection(moveDirection) * speed * Time.fixedDeltaTime);
    }
}
```

This script includes basic movement, running, crouching, and jumping. It also includes a stamina system for running. You'll need to add your own camera system, headbobbing, footsteps, and breathing system as needed.