A long long time ago, I wrote a blog post showing how to create db_executor role in SQL Server. There is a reader and a writer role but no execute role. So if you wanted a role that allowed you grant execute to all stored procedures and functions in a SQL Server database, you need to create a user-defined role
That blog post is the most read post on my blog even if it is nearly nine years old. So I decided to make a YouTube video from it
I won't re-post the original blog, I'll leave that back in 2010 but I have updated the old blog post to include the video and you can also watch the video here too.