plodder (n.)

• dawdler
• drone
• drudge
• fag
• goldbrick
• goof-off
• grind
• grub
• hack
• laggard
• lie-abed
• lingerer
• loiterer
• procrastinator
• slave
• sleepyhead
• slogger
• slowpoke
• slug
• sluggard
• snail
• stick-in-the-mud
• swot
• tortoise
• workhorse