Buddy or peer mentors. In the early stages of a person's career, a "buddy" can help speed up the learning curve. This relationship helps the protégé understand how things work at the organization.
Career mentors. After the initial period at a workplace, employees need to have a senior manager serve as a career advisor and advocate.
Life mentors. A life mentor serves as a periodic sounding board when one is faced with a career challenge. Organizations can't necessarily offer a life mentor but they can encourage seeking one.