The present disclosure provides a fastener and a fastener assembly. The fastener includes a position limit column, an elastic member, and at least one fastening hook. The elastic member is disposed at a bottom portion of the position limit column, the first fixing member includes a fastening hole disposed at a portion corresponding to the fastening hook, and the first fixing member includes a position limit hole disposed at a portion corresponding to the position limit column. When the fastener moves to a predetermined position, the position limit column falls into the position limit hole and the fastening hook engages with the fastening hole, thus, the fastener is fixedly connected with the first fixing member. This kind of fastener has a simple structure and does not need screws for mounting. Mounting and dismounting do not need professional tools, and are convenient and efficient. Thus, this fastener can reduce manpower cost and time cost.