Here are five of the world’s top-known coaches and their fields, recognized for their impact and influence:

1. Tony Robbins (Life and Business Coaching)

Field: Personal development, leadership, and business strategy.

Notable Achievements:

Renowned for his motivational seminars, including Unleash the Power Within and Date with Destiny.

Author of bestsellers like Awaken the Giant Within and Unlimited Power.

Has coached leaders like Bill Clinton, Serena Williams, and Oprah Winfrey.

2. Marshall Goldsmith (Executive Coaching)

Field: Leadership development and executive coaching.

Notable Achievements:

Author of What Got You Here Won’t Get You There and Triggers.

Ranked as the #1 executive coach by Thinkers50.

Has worked with top CEOs and executives of Fortune 500 companies.

3. Robin Sharma (Leadership Coaching)

Field: Personal mastery and leadership development.

Notable Achievements:

Author of The Monk Who Sold His Ferrari and The Leader Who Had No Title.

Known for coaching leaders and organizations on creating lasting impact and success.

4. Tim Grover (Sports Performance Coaching)

Field: Elite sports performance and mental toughness.

Notable Achievements:

Known for coaching iconic athletes like Michael Jordan, Kobe Bryant, and Dwyane Wade.

Author of Relentless: From Good to Great to Unstoppable.

Focuses on the mindset and work ethic needed for peak athletic performance.

5. Iyanla Vanzant (Spiritual and Personal Growth Coaching)

Field: Spiritual development, healing, and self-empowerment.

Notable Achievements:

Host of Iyanla: Fix My Life on Oprah Winfrey Network (OWN).

Author of books like Yesterday, I Cried and Acts of Faith.

Recognized for her transformative work in helping individuals overcome personal challenges and find inner peace.

Each of these coaches has excelled in their respective domains, inspiring millions worldwide with their insights, methods, and teachings.

Coaching is a collaborative process where a trained professional (the coach) helps an individual or group to achieve specific personal or professional goals. It's about unlocking potential and guiding individuals towards self-discovery and growth.

The '...is it necessary' component of this question caught my eye.

For what it's worth, my view would be 'yes, coaching is necessary, at particular points in a person's career, or in specific situations'.

Coaching can enable people to stop and reflect on a particular challenge, setback, problem or decision they wish to deal with. They use the coach as a sounding board, not for advice or to tell them what to do, but as someone who will question and challenge, enabling them to work through and resolve the issue for themselves. If coaching clients are resourceful and motivated, then likely a coaching approach will work well.

Telling people what to do (directing) and advice giving (mentoring) are obviously different approaches. In my experience, a coaching approach can build competence and confidence in those who are technically proficient, but looking to develop and work more independently - ultimately, coaching is a gateway to delegation.

If you wish to develop people such that you can delegate, then taking a coaching approach will be necessary.

These are my reflections on this, partly inspired by real-life and to some extent by the ever useful, 'situational leadership' model which of course, involves directing, mentoring, coaching and delegating.

Good luck and best wishes with your research/work.