There are several highly regarded online courses available for developing leadership skills. Here are some of the best online courses for leadership:

1. Leadership and Emotional Intelligence by Coursera: Offered by Case Western Reserve University, this course explores the concept of emotional intelligence and its role in effective leadership. It focuses on developing self-awareness, self-management, social awareness, and relationship management skills.

1. Leading People and Teams Specialization by Coursera: This specialization, provided by the University of Michigan, covers various aspects of effective leadership, including motivation, teamwork, and conflict resolution. It offers practical strategies for leading individuals and teams to achieve organizational goals.

1. Authentic Leadership Development by Harvard Business School Online: This course focuses on developing authentic leadership skills based on self-awareness, empathy, and ethical decision-making. It helps leaders understand their personal values, strengths, and weaknesses to lead with integrity.

1. Leadership in the Digital Age by MIT Sloan School of Management: This course explores the challenges and opportunities of leading in the digital era. It covers topics such as digital transformation, data analytics, and innovation in the context of leadership.

1. Adaptive Leadership: Mobilizing for Change by edX: Offered by the Harvard Kennedy School, this course teaches adaptive leadership principles for driving change in complex situations. It provides frameworks and strategies to tackle adaptive challenges and mobilize others towards shared goals.

1. Leading Through Influence by LinkedIn Learning: This course focuses on developing influential leadership skills. It covers techniques for building credibility, communicating persuasively, and leading without formal authority.

1. The Science of Leadership by Udemy: This course combines scientific research and practical insights to explore effective leadership principles. It covers topics like motivation, decision-making, communication, and building high-performing teams.

Remember to consider factors such as course content, instructor expertise, user reviews, and your specific leadership development needs when choosing an online course. Additionally, some universities and institutions offer leadership development programs or executive education certificates that include multiple courses focused on leadership.