Your dissertation director. Other graduate faculty. Grad students who are further along than you. Postdocs.
Your peers on the job market. People you meet at conferences.
People who write you tenure letters (i.e., those you put on your list, after the letters are over). Your dissertation director’s other students.
Go up to successful people at conferences, ask if they have a minute, introduce yourself, ask one focused question. People one step ahead of you. People who have switched careers. People in different departments.
Listserves and mailing lists through your professional organizations. Do they have a mentoring group? Senior members of whatever professional/academic organizations you are part of.
Propose a symposium at a conference and ask senior people to be on it. Now you have a connection.
A formal mentoring program on campus. The campus faculty development center. Other senior faculty you meet around campus; take them for coffee. Try to form a writing group or grant development group.
Your former boss. People your dissertation director or boss introduces you to. Any retired faculty you can find. The faculty ombudsperson.