Methods and apparatus relating to lightweight trusted tasks are disclosed. In one embodiment, a processor includes a memory interface to a memory to store code, data, and stack segments for a lightweight-trusted task (LTT) mode task and for another task, a LTT control and status register including a lock bit, a processor core to enable LTT-mode, configure the LTT-mode task, and lock down the configuration by writing the lock bit, and a memory protection circuit to: receive a memory access request from the memory interface, the memory access request being associated with the other task, determine whether the memory access request is attempting to access a protected memory region of the LTT-mode task, and protect against the memory access request accessing the protected memory region of the LTT-mode task, regardless of a privilege level of the other task, and regardless of whether the other task is also a LTT-mode task.