Another resource intensive bot is Ahrefs bot. It doesn't serve any public purpose and solely made to crawl your website for any potential competitors to give advantage.
I came up with a list of bots that is abusive in nature.
You may want to remove advertising bots from the list if you're using google adsense or adwords.
[CODE title="robots.txt"]
#Huge offenders
#adsbot
User-agent: adsbot
Disallow: /
#BLEXbot webmeup-crawler
User-agent: BLEXBot
Disallow: /
#Semrush bots
User-agent: SemrushBot
Disallow: /
#Ashref bots
User-agent: AhrefsBot
Disallow: /
# http://mj12bot.com/
User-agent: MJ12bot
Disallow: /
# advertising-related bots:
User-agent: Mediapartners-Google*
Disallow: /
# Crawlers that are kind enough to obey, but which we'd rather not have
# unless they're feeding search engines.
User-agent: UbiCrawler
Disallow: /
User-agent: DOC
Disallow: /
User-agent: Zao
Disallow: /
# Some bots are known to be trouble, particularly those designed to copy
# entire sites. Please obey robots.txt.
User-agent: sitecheck.internetseer.com
Disallow: /
User-agent: Zealbot
Disallow: /
User-agent: MSIECrawler
Disallow: /
User-agent: SiteSnagger
Disallow: /
User-agent: WebStripper
Disallow: /
User-agent: WebCopier
Disallow: /
User-agent: Fetch
Disallow: /
User-agent: Offline Explorer
Disallow: /
User-agent: Teleport
Disallow: /
User-agent: TeleportPro
Disallow: /
User-agent: WebZIP
Disallow: /
User-agent: linko
Disallow: /
User-agent: HTTrack
Disallow: /
User-agent: Microsoft.URL.Control
Disallow: /
User-agent: Xenu
Disallow: /
User-agent: larbin
Disallow: /
User-agent: libwww
Disallow: /
User-agent: ZyBORG
Disallow: /
User-agent: Download Ninja
Disallow: /
# Misbehaving: requests much too fast:
User-agent: fast
Disallow: /
#
# Sorry, wget in its recursive mode is a frequent problem.
# Please read the man page and use it properly; there is a
# --wait option you can use to set the delay between hits,
# for instance.
#
User-agent: wget
Disallow: /
#
# The 'grub' distributed client has been very poorly behaved.
#
User-agent: grub-client
Disallow: /
#
# Doesn't follow robots.txt anyway, but...
#
User-agent: k2spider
Disallow: /
#
# Hits many times per second, not acceptable
# http://www.nameprotect.com/botinfo.html
User-agent: NPBot
Disallow: /
# A capture bot, downloads gazillions of pages with no public benefit
# http://www.webreaper.net/
User-agent: WebReaper
Disallow: /
[/CODE]