you can user sorted..reverse as per doc

def main():
   print('Celebrities  known by one name:')
   drake = ['Drake']
   BE = ['Beyonce']
   RI = ['Rihanna']
   BO = ['Bono']

   a = input('Enter another one name celebrity ')
   b = input('Enter another one name celebrity ')
   c = input('Enter another one name celebrity ')
   d = [a,b,c,drake,BE,RI,BO]
   f = sorted(d,reverse=True)
   print('Celebrities in Reverse Alpha Order')
   for d in f:
      print(d)
main()

Try this,

sorted('abcdef',reverse=True)

using System.Linq;

//...

string f = "abcdefghijklmmlkjihgfedcba"
string r = new string(f.Reverse().ToArray());

Redefine arguments for 'category' taxonomy ONLY:

add_filter( 'get_terms_args', 'my_term_args', 10, 2 );

function my_term_args( $args, $taxonomies ) {
    // don't affect admin area passing back default arguments
    if ( is_admin() ) {
        return $args;
    }

    // check the taxonomy in use and redefine it's default arguments
    if( in_array( 'category', $taxonomies ) ) {
        $args['orderby']    = 'name';
        $args['order']      = 'DESC';
        $args['hide_empty'] = false;
    }

    return $args;
}

Also, get_terms() syntax you've posted is obsolete since version 4.5. The new syntax look like this:

<?php
$categories = get_terms( array(
    'taxonomy'   => 'category'
    'orderby'    => 'name',
    'order'      => 'DESC',
    'hide_empty' => false
) );

Just use the reversed function:

a = list(reversed(sorted(a, key=lambda x: (-len(x), x))))

In [301]: a                                                                                                                                        
Out[301]: ['b', 'a', 'zzz', 'ddd', 'ccc']