Someone whose job is to speak for someone's case in a court of law; a counsel.
Anyone who argues the case of another; an intercessor.
A person who speaks in support of something.
A person who supports others to make their voices heard, or ideally for them to speak up for themselves.
To plead in favour of; to defend by argument, before a tribunal or the public; to support, vindicate, or recommend publicly.
To encourage support for something.
(with for) To engage in advocacy.